Water-soluble substance extracted from the coralline alga, Corallina pilulifera have the effect of induction of larval metamorphosis on the sea urchins, Pseudocentrotus depressus and Anthocidaris crassispina.
The chemical cue for larval metamorphosis of P. depressus in the solution was heat stable and remained active even if its treated with organic solvent. Concentration of the potassium in an active fraction was not so high to induce the larval metamorphosis. The cue could be other inorganic ions or organic substances.