One of a peculiar kind of internal buds, or germs, produced in the interior of certain Bryozoa and sponges, especially in the fresh-water species; -- also called winter buds
. [1913 Webster
" They are protected by a firm covering, and are usually destined to perpetuate the species during the winter season. They burst open and develop in the spring. In some fresh-water sponges they serve to preserve the species during the dry season. See Illust. under Phylactolæmata."