 After swimming for a few days the larvae sink and crawl until they find a place to settle.Most of the cells transform into archeocytes and then into the types appropriate for their locations in a miniature adult sponge.Glass sponge embryos start by dividing into separate cells, but once 32 cells have formed they rapidly transform into larvae that externally are ovoid with a band of cilia round the middle that they use for movement, but internally have the typical glass sponge structure of spicules with a cobweb-like main syncitium draped around and between them and choanosyncytia with multiple collar bodies in the center.