An algae-extracted gelling agent, sodium alginate is used in molecular gastronomy in association with calcium salts for the basic spherification and reverse-spherification processes, whether to make small caviar-like pearls or large ravioles. Sodium alginate is therefore a salt extracted from the viscous liquid from the cell wall of brown algae. Its natural function is to increase the flexibility of the algae. Thus, algae developing in troubled waters generally have larger alginate content than those growing in calm waters.