Entoloma Posted October 16, 2023 Share Posted October 16, 2023 A few months ago, I came across this big crab concretion sticking out of the sand. It was my second largest of the day, but only by a mere 10kg! Still! 12kg aint too bad. Where I found it, was quite sandy, and another fossil hunter had been there before me, but fortunately he hugged the cliff face, there and back. I walked towards the ocean and spied some legs sticking out of the sand! I started this prep with my ZOIC chicago and rounded chisel tip. It removed 2kg of rock in two hours. Not the fastest, but it beats my old dremel by a long shot! 1 Link to comment Share on other sites More sharing options...
Entoloma Posted October 16, 2023 Author Share Posted October 16, 2023 This is after the first session of two hours of matrix removal 1 Link to comment Share on other sites More sharing options...
Entoloma Posted October 16, 2023 Author Share Posted October 16, 2023 I finally hit the carapace on the second session, but its sticky! Millimetre by millimetre, I am removing rock. It seems to look quite a nice colour though. This is my progress after the second day, which was 4 hours 2 Link to comment Share on other sites More sharing options...
Entoloma Posted October 16, 2023 Author Share Posted October 16, 2023 Another 4 hour session today, and the carpace is looking good, albeit still sticky! Slow and steady though.... The interesting thing with this crab, is it actually had a tube worm stuck to its carapace, unfortunately I was not able to save it. Towards the rear of the carapace, and there is a bit of pyrite speckled too, which is odd. Not seen that before 6 Link to comment Share on other sites More sharing options...
RJB Posted October 16, 2023 Share Posted October 16, 2023 Lookin good. The shape of that conc tells me you may have a very large right claw or the left one may be tucked in a bit? Best of luck. Looking forward to seeing your progress RB 1 Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted October 16, 2023 Share Posted October 16, 2023 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
trilobites_are_awesome Posted October 16, 2023 Share Posted October 16, 2023 I love new Zealand crabs. Cheers! James Link to comment Share on other sites More sharing options...
Ptychodus04 Posted October 16, 2023 Share Posted October 16, 2023 I have a massive concretion in my lab just waiting for me to get time to prep it... @Entoloma your crab is looking good already. Sticky crabs are no fun. Regards, Kris Global Paleo Services, LLC https://globalpaleoservices.com http://instagram.com/globalpaleoservices http://instagram.com/kris.howe Link to comment Share on other sites More sharing options...
Entoloma Posted October 18, 2023 Author Share Posted October 18, 2023 I worked almost four and half hours on my pet today, and I can now feel comfortable to work on the legs for a bit. The leg im working on currently seems great on one half where its brown, but pretty rotten on the pale side... Still! its staying intact well enough, so thats a bonus! I am unsure what the best plan of attack is for this next leg that is split in two. Should I start from the inside, and follow the leg out? Or just stumble my way from the outside and work in? Heres the progress 1 Link to comment Share on other sites More sharing options...
Ptychodus04 Posted October 18, 2023 Share Posted October 18, 2023 5 hours ago, Entoloma said: Should I start from the inside, and follow the leg out? Or just stumble my way from the outside and work in? I like to work carapace out on crabs. Maybe just personal preference but I find that there's less guessing that way. 1 Regards, Kris Global Paleo Services, LLC https://globalpaleoservices.com http://instagram.com/globalpaleoservices http://instagram.com/kris.howe Link to comment Share on other sites More sharing options...
RJB Posted October 18, 2023 Share Posted October 18, 2023 I almost always go down the back of the carapace and find the rear end, then follow those first legs out from that first joint called the coxa. RB 1 Link to comment Share on other sites More sharing options...
mr.cheese Posted October 18, 2023 Share Posted October 18, 2023 I am enjoying this thread! I have just started on my first bit of prep on a crab claw with a dremel, really enjoying it. Anyway....I have a few questions about your one. When you say you saw a few legs sticking up you mean the tiny trace lines of what I assume is broken leg ends, basically what is in your last picture above? Just so I can help with getting my eye in a little when I am walking. The other question is a little more general but I just wondered as RJB mentioned there should be a big claw etc. What makes a fossil be contained in a nodule type thing? It seems many times the erosion is very even and leaves the bulk of the fossil in the middle as it gets worn away. I sell a lot of Ammonites and Mazon Creek ferns and they are all nicely in the middle of a nodule? Could just be the ones I see are the ones that were worth keeping I guess, but you were confident there was a crab in the middle and it wasn't just the remains of a claw barely in a rock. I hope that all makes sense?! Link to comment Share on other sites More sharing options...
jpc Posted October 18, 2023 Share Posted October 18, 2023 1 hour ago, mr.cheese said: What makes a fossil be contained in a nodule type thing? It seems many times the erosion is very even and leaves the bulk of the fossil in the middle as it gets worn away. I sell a lot of Ammonites and Mazon Creek ferns and they are all nicely in the middle of a nodule? Could just be the ones I see are the ones that were worth keeping I guess, but you were confident there was a crab in the middle and it wasn't just the remains of a claw barely in a rock. I Concretions are said to form by a combination of decomposition chemicals and minerals in the surrounding silt/sand/mud etc. So they form from the inside outwards. This is why they often do not completely encase the fossil; they stopped forming when only the leg tips were sticking out of this poor little dead crab. Yes, the thin orange lines on the edge of the concretion are the cross sections of legs. 1 Link to comment Share on other sites More sharing options...
Entoloma Posted October 18, 2023 Author Share Posted October 18, 2023 6 hours ago, mr.cheese said: I am enjoying this thread! I have just started on my first bit of prep on a crab claw with a dremel, really enjoying it. Anyway....I have a few questions about your one. When you say you saw a few legs sticking up you mean the tiny trace lines of what I assume is broken leg ends, basically what is in your last picture above? Just so I can help with getting my eye in a little when I am walking. The other question is a little more general but I just wondered as RJB mentioned there should be a big claw etc. What makes a fossil be contained in a nodule type thing? It seems many times the erosion is very even and leaves the bulk of the fossil in the middle as it gets worn away. I sell a lot of Ammonites and Mazon Creek ferns and they are all nicely in the middle of a nodule? Could just be the ones I see are the ones that were worth keeping I guess, but you were confident there was a crab in the middle and it wasn't just the remains of a claw barely in a rock. I hope that all makes sense?! As already mentioned, yes, the leg rings are a dead giveaway. Sometimes the concretion doesn't naturally form around the whole crab, exposing the carapace and claws as well. It all depends on the amounts of calcium and carbon being released when forming the concretion, as the crab decomposes. If you're really lucky, all legs will be inside the concretion, but normally they are in the sediment, outside the concretion. They are normally found in oval or circular shapes that aren't too flat. 1 Link to comment Share on other sites More sharing options...
mr.cheese Posted October 19, 2023 Share Posted October 19, 2023 Thank you for that, will help me spot more things hopefully! Interesting how the concretion occurs too. Sorry for hijacking the topic! Link to comment Share on other sites More sharing options...
Entoloma Posted October 21, 2023 Author Share Posted October 21, 2023 A few small sessions have gone by without feeling like I was making much progress, but there ya go. This crab is taking quite a while, with a few problems. I exposed the rear end of the crab, and luckily, everything was nicely attached, so thats good. Working from the left legs of the crab first, I soon encountered a big problem. One of the legs was missing the top section of it! I had to really think about what I would do, and get around this problem. I thought about possibly eradicating that leg all together, and exposing the other three legs, though it seemed to me like not doing the crab justice, and being a bit misleading to how the crab really looked when this project is all said and done! I decided I would hollow this leg out, so I can expose whats naturally there. 3.5 legs is better than 3 I suppose! This effort took around 2 or 3 hours, and was very sticky, which was a pain, because all the other legs are nice and flake away nicely. Anyway! Heres some photos 2 Link to comment Share on other sites More sharing options...
Ludwigia Posted October 21, 2023 Share Posted October 21, 2023 You're doing a great job so far. I would say you made the right decision on that leg. Looks good! Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
RJB Posted October 21, 2023 Share Posted October 21, 2023 Hey man, great going on that leg! RB Link to comment Share on other sites More sharing options...
mr.cheese Posted October 21, 2023 Share Posted October 21, 2023 I think you did the right thing as when you look at it you see all the legs still hollow or not it still gives the shape etc. Very good thinking and good work too, I am enjoying this thread and looking forwards to updates! Link to comment Share on other sites More sharing options...
Ptychodus04 Posted October 23, 2023 Share Posted October 23, 2023 Good call on the leg. I would have done the same thing. Regards, Kris Global Paleo Services, LLC https://globalpaleoservices.com http://instagram.com/globalpaleoservices http://instagram.com/kris.howe Link to comment Share on other sites More sharing options...
Entoloma Posted October 28, 2023 Author Share Posted October 28, 2023 (edited) A few hours of prepping have past since my last update. Full of ups and downs. Partially sticky legs and damage to a joint due to me not expecting it! Neverless, its turning out great. I cant wait to work on the claws, but I have a bit more tidying up to do on the right hand side. I am 31 hours in currently. Edited October 28, 2023 by Entoloma 3 Link to comment Share on other sites More sharing options...
RJB Posted October 28, 2023 Share Posted October 28, 2023 Lookin good Entoloma! RB Link to comment Share on other sites More sharing options...
Entoloma Posted October 30, 2023 Author Share Posted October 30, 2023 One more session! The right side of the legs are done, and so is most of the merlus. They still need touch ups, but thats final stage stuff! The carpus is pretty dang big, and hopefully this claw is too. As soon as I got to the propodus, it started flaking away from the rock beautifully. The best separation out of the rest of the crab! I was loving it.... I packed up for the day and decided to clean the scribe. As I unscrewed it, the drive pin in my CP9361 had broke on one side, and half of it fell out! Im not sure how serious that is, how it happened, but I will get it fixed before I start again. Just when I was on to the meat of the crab too! Link to comment Share on other sites More sharing options...
Doctor Mud Posted October 30, 2023 Share Posted October 30, 2023 (edited) Nice work on the crab! isn’t that pin that secures the piston housing on? I think that pin (which is hollow = rolled steel) goes right through. normally you would need to push it out to take off the housing. So should be an easy fix. Looks similar to the ME-9100 and I’ve pulled one apart a few times to replace parts Edited October 30, 2023 by Doctor Mud 1 Link to comment Share on other sites More sharing options...
Entoloma Posted October 30, 2023 Author Share Posted October 30, 2023 30 minutes ago, Doctor Mud said: Nice work on the crab! isn’t that pin that secures the piston housing on? I think that pin (which is hollow = rolled steel) goes right through. normally you would need to push it out to take off the housing. So should be an easy fix. Looks similar to the ME-9100 and I’ve pulled one apart a few times to replace parts Thanks! Yeah, the drive mechanism is a Chicago CP9361. I will go to the store tomorrow and see if I can find a replacement roll pin. It shouldn't be a specialised part, which is good Link to comment Share on other sites More sharing options...
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