Platyceramus

Platyceramus was a genus of Cretaceous bivalve molluscs belonging to the extinct inoceramid lineage. It is sometimes classified as a subgenus of Inoceramus.

The largest and best known species is P. platinus. Individuals of this species typically reached 1 m (3 feet 3 inches) or more in axial length, but fossil specimens 3 m (nearly 10 feet) long have been found, making it the largest bivalve yet found. Its huge but very thin shell often provided shelter for schools of small fish, some of which became trapped and fossilized themselves, and the outer shell often provided habitat for oysters and barnacles. Shells containing pearls have also been discovered.