A fossil sponge from the Permian Fort Apache Limestone

[Arizona Chris]

Hi all,

 

Fort Apache sponges are quite uncommon, only one sizable specimen was obtained from over 200 pounds in rock. But it is well preserved, and show the major features of fossil sponges from the Paleozoic. To be more precise, from our first locality, where nearly all the ostracods came from - we had no sponge material at all. The second new site, a half a mile further down the trail produced this specimen from about 35 pounds in limestone. They were also with numerous bryozoans and gastropods in the same mix. The one sponge we found is a calcareous type sponge that have been preserved by silica replacement.  What I dont know is if this is a part of a big flat sponge, or perhaps a section of a tubular one.  Maybe some of you can ascertain that.

 

This is the largest specimen we found, it was in a class by itself! About 4 cm long and about 1 cm thick, this fragment of a large irregular sponge had excellent pore and ostium details. A millimeter scale is at bottom. 3.5x view

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 A closer 7x view of its surface reveals the very "spongy" appearance of the type you might wash your car with. The holes are the pores which take in water to an interior cavity for respiration and feeding on plankton. If this was a part of a large flat sponge, those larger holes might be the osculums and the tiny surface pores the in current holes.

 

Even closer at 20x, this shows the pore details more clearly in a massive 16 focus layers stacked image.

 

There have been a few false alarms on these calcareous sponges.  Some of the really worn down bryozoans that are wrapped around urchin spines  look indeed like a tubular sponge!  We continue to look.  This last weekend, me and my auxilliary rock hauler - I mean my wife - packed out another 36 pounds of promising rock from the second richer locality along the Highway 260 Trail east of Payson here in Arizona.  We hope to find more!

 

Thanks for looking, its a pleasure for us to show what we have found so far!

[ynot]

Nice! Thanks for sharing.

[caldigger]

Ha, let's see an ant push that one out of their hole!