Wikipedia
Cassianellidae
Cassianellidae is a small extinct family of prehistoric bivalves which lived from the Middle Triassic, Ladinian stage through the Late Triassic Norian stage. It has been suggested that the family may have evolved from the related family Bakevelliidae. Bakevelliidae species are found in North America, South America, Europe, the Middle East, and Asia. Living a stationary life attached to substrate in marine and brackish envoronments, they formed shells of an aragonite composition with a low amount of magnesium calcite. The family Cassianellidae was named by K. Ichikawa in 1958.