21. These are both brachiopods (not clams). Without knowing anything about the biology of brachiopods, choose the fossil that is preserved as original shell material. What is your evidence (you should ...

The clam's small size and unique appearance ... an amateur shell collector who had first recognized the fossil's distinctiveness among thousands of shells. Valentich-Scott, upon seeing the ...

Pterotrigonia wasn't just any clam; it was part of a family of mollusks known for their ribbed shells, something that made them stand out both during their time on the planet and in the fossil ...