What is the parasitic larval stage of many freshwater bivalves called?

The parasitic larval stage of many freshwater bivalves, particularly those in the family Unionidae, is called a glochidium. Glochidia are specialized larvae that attach to the gills or fins of fish, where they remain until they metamorphose into juvenile bivalves. This stage is crucial for the dispersal and survival of the species, as it allows them to exploit the mobility of fish hosts.