Here is another macro shot of a scallop shell. The little rocks are sand, giving a good sense of scale.
Barnacles were another common fossil form, looking very much the same as they do today. This is a ribbed barnacle showing what may be the actual creature that lived inside the shell in the opening at the left end of the fossil. The concentric rings are a clue that it isn't simply mud there, but it isn't shell either.
I wasn't sure what to make of this small stone. How the striations might have been formed was what piqued my interest in it.