Broedenzymen

The emperor specimen's eggs are attached to some form of incubator.

In a normal life cycle it seems likely that sea emperors would have buried their eggs in shallower waters, where different organic materials in the soil would have triggered a hatching response. The incubator suggests the aliens had resorted to developing artificial hatching enzymes which would simulate the eggs' natural hatching environment, but were unable to discover the formula.

With extensive information on the sea emperors themselves it may still be possible to fabricate an artificial hatching enzyme using indigenous ingredients, however the only surviving source of that information may be the sea emperor itself.