Today's curious finds

[HeatherMF]

Interesting little 'rocks' from today. 2 may be nothing, 2 I'm pretty sure about, and 2, seem to be imprints. Hope you guys can tell me. Again, Half Moon Bay. Also, how do I clean these?

[Doctor Mud]

Hi there,

 

These look like the remains of shells - molluscs.

 

Some are internal molds of Gastropods "snails" the coils, while others are from bivalves.

 

Neat finds.

I probably wouldn't clean them as they are casts or molds and made of rock. Cleaning wouldn't expose any new fossil,

 

Enjoy as is.

[trisk]

Top middle looks like it has some shell inclusions and might be a cast, hard to tell from this angle. Bottom right looks like a weathered piece of oyster shell from the surface texture. The two gastropods are probably the same as the one you found earlier. Far left is a cast of a ribbed bivalve (maybe the scallop Pecten from the Cretaceous or later, haven't found anything definitive about the local geology). Bottom middle are shell fragments of another bivalve.