Panopea (?) micro fossil.

[OregonFossil]

This specimen from the Oligocene Keasey formation is 5mm long. This shale is extremely hard, I had to use the 3 pound hammer to break it. The rock it was encased in was 8 x 9" and this was the only fossil I could find after breaking all in 1-3" pieces. Image is a Olympus Macro 60mm image on a Panasonic G9 camera using flash. Do you consider a fossil of this size a Micro fossil?

 

I am going to leave it in the matrix because I've tried  dental tools on this particular shale and it is just too hard.

 

Need to do some further work on the ID with external shell features/geometry, but I think I am close.

[Thomas.Dodson]

4 hours ago, OregonFossil said:

 Do you consider a fossil of this size a Micro fossil?

I don't think I've ever seen a consensus on what constitutes a microfossil (despite the name) but this seems rather big to me. I collect a lot smaller specimens using ordinary macrofossil techniques but that's me.

4 hours ago, OregonFossil said:

Need to do some further work on the ID with external shell features/geometry, but I think I am close.

It does resemble Panopea but it also resembles a lot of other things. It's hard to draw a conclusion without preparing it further.