A few weeks ago, my niece and I made a trip to the Straits of Juan de Fuca. I believe we were in the Pysht formation.
We cracked several concretions open, but this was the only one I found anything in (my niece found something equally as interesting). We found other neat things that I will post up later.
It is about 8mm at the largest exposed portion (see photo). It looks segmented like a shrimp tail, which made me think of the Aturia I've seen from other locations here in Washington. Just a guess, though.
Your thoughts would be appreciated.
I will continue the prep on this, after I get the Microjack.