Anatomical diagram of a hypothetical ancestral mollusc
The evolution of the molluscs is the way in which the Mollusca, one of the largest groups of invertebrate animals, evolved. This phylum includes gastropods, bivalves, scaphopods, cephalopods, and several other groups. The fossil record of mollusks is relatively complete, and they are well represented in most fossil-bearing marine strata. Very early organisms which have dubiously[further explanation needed] been compared to molluscs include Kimberella and Odontogriphus.