The new "Unknown Invertebrate from the Leighton Formation"

[Mainefossils]

I am really puzzled on this new one, I have explored phyllocarids, trilobites, and many others, and can't seem to find a good match for it. I am not absolutely positive it is a fossil though, just the surface texture and way it prepped makes me think it is. It is from the Leighton Fm, which is Silurian, Pridoli. 

 

When I first started prepping this, I was under the impression that this was the internal mold of a Chonetes bastini, which is why I started on it. I soon discovered though that it couldn't be from a brachiopod, and now I am stumped on it. The first specimen is completely prepped out, it is labelled SA in the photo. In the process of prep, I also found a new piece that exhibited the same surface-texture (labelled SB in picture), and could be a part of the first specimen. 

 

Below are a few pictures of it. The first is of the specimen before prep - this is the only picture I have, and shows everything that was exposed. It was taken from the top of specimen SA. The next picture was taken from above, it shows the two specimens (SA and SB) and their relation to each other. The third picture shows the specimen that is on the upper left (SA), the fourth shows the specimen on the lower right (SB).

 

Thanks in advance for your help!

 

 

 

 

[Wrangellian]

Slickensides?

[Mainefossils]

16 hours ago, Wrangellian said:

Slickensides?

Interesting... That would make sense though, given the state of the shale and the other specimens. I just didn't think that they would occur in such an isolated fashion. Thanks for your help! 

[Wrangellian]

I've seen them around here in isolated 'blobs' similar to this. As far as I know they're never extensive anyway. Usually they occur on the sides of concretions (what yours appears to me) or on the side of a fossil, or some other area of unevenness.