The Pacific Beetle Cockroach is the only known viviparous cockroach. The pregnant females provide nutrition to the embryos by secreting milk proteins (Lili-Mips), which crystallize in vivo. The crystals that grow in the embryo are heterogeneous in their protein sequence. It is not apparent from the structure determined what role heterogeneity and glycosylation played in crystallization. Lili-Mips are very nutritious.