Calcium plays a fundamental role in the life of snails, regulating different processes such as motility, growth and cell division. Calcium directly influences shell growth, fecundity, oviposition, mortality, internal metabolism and homeostasis. The objective of this work was to describe the formation of pearls in Biomphalaria glabrata exposed to different amounts of calcium carbonate under laboratory conditions. Pearls were observed in the digestive gland and intestine in the group of snails exposed to 20 and 60 mg /L of calcium carbonate after 45 days. The results show that snails produce pearls as a calcium reservoir before reaching sexual maturity.