LaForge and Page studied B. californica development. The species lays its eggs in a coiled ribbon attached to the substrate along one edge. The egg ribbon is white, about 1 cm wide, and 1 mm thick. The egg capsules in the ribbon are oval, around 1.6 or 1.7 mm wide, and contain 1-2 eggs each. At 11-12 C the eggs hatched as veliger larvae in 19 days. Its developmental pattern resembles that of nudibranchs more closely than does that of other pleurobranchoideans which have been studied. They also discovered that the snail-like shell which the larva has only becomes bilaterally symmetrical late in development. Some of the events that occurred when the larva settled and metamorphosed into the adult form included a rapid expansion of the mantle over the shell so that the shell became internal. They also lost the large larval velar lobes and began growing the rhinophore and oral veil. The larva also appeared to have an ospradium (chemosensory organ), though the adult does not.