Vauxia Burgess Shale Sponge Fossil

Description: This is an as unusual member of the Desmospongia, the most diverse of modern-day sponges. Greater than 90% of the extant 5,000 known species of sponges are desmosponges. Such a representation in the fossil record is not maintained where less than half the known genera are of this type, a consequence of the fact that the skeletons do not fossilize readily. Desmosponge skeletons are composed of spongin fibers and/or siliceous spicules. Sponges are known from the late Precambrian, with few localities contributing to the fossil record over time. The Burgess Shale Fauna is one such fossil lagerstatte. The specimen is a member of the family Vauxiidae with this one being the patronymic genus. Unlike all other Burgess sponges, this one is composed only of a sponging-like material with no spicules. The fibers that made up the skeleton are fused into a net affording a tough structure that preserved well. If you look closely, you can see the pores present with which the sponge took up water to filter out the particulates upon which it fed. Since the location has been declared a World Heritage site, only specimens from old collections such as this are available.