Temporal range: Cretaceous
|A cast of a Platyceramus platinus fossil|
The largest and best known species is Platyceramus platinus. Individuals of this species typically reached 1 m (3 ft 3 in) or more in axial length, but fossil specimens 3 m (nearly 10 feet) long have been found, making it the largest known bivalve. Its huge but very thin shell often provided shelter for schools of small fish, some of which became trapped and fossilised themselves. The outer shell often provided habitat for its own juveniles, also for oysters such as the epizootic oyster Pseudoperna congesta as shown in the image here, and barnacles.
Shells containing pearls have also been discovered.