Allows the sea urchin to digest the protective envelope derived from the egg extracellular matrix; thus allowing the sea urchin to swim freely. Hydrolysis of proteins of the fertilization envelope and dimethylcasein. Binds 1 zinc ion per subunit. During hatching, the 50 kDa mature enzyme is autocatalytically cleaved to produce a major 38 kDa and a minor 15 kDa form which may be disulfide linked. Subsequent cleavage of the 38 kDa species yields a 32 kDa non-specific protease. Embryo, blastula stage. Highest activity at 12.5 hours embryo stage. There are two distinct domains in this protein; the catalytic N-terminal, and the C-terminal which is involved in substrate specificity. The conserved cysteine present in the cysteine-switch motif binds the catalytic zinc ion, thus inhibiting the enzyme. The dissociation of the cysteine from the zinc ion upon the activation-peptide release activates the enzyme. Belongs to the peptidase M10A family.