sentences:  Most species have prominent growth lines which appear as raised semicircles concentric to the growing edge of the shell.Paleontologists suggest that the giant size of some species was an adaptation for life in the murky bottom waters, with a correspondingly large gill area that would have allowed the animal to survive in oxygen-deficient waters.Species of "Inoceramus" had a worldwide distribution during the Cretaceous and Jurassic periods (from 189.6 to 66.043 Ma).