 Capable of living for up to 130 years, the freshwater pearl mussel begins life as a tiny larva, measuring just 0.6 to 0.7 millimetres long, which is ejected into the water from an adult mussel in a mass of one to four million other larvae.This remarkable event takes place over just one to two days, sometime between July and September.The larvae, known as glochidia, resemble tiny mussels, but their minute shells are held open until they snap shut on a suitable host.