The sponge fossil record extends to 635 million years ago, and is considered the oldest multicellular animals to inhabit the Earth. The importance of these animals is their structure, which allowed them to survive until Recent times and their role in the marine environment preventing harmful ecosystems changes. The NHM has more than 71,000 fossil sponges from all around the world (Africa, Antarctica, Australia, Asia, Central America, Europe, the Middle East, North America, Russia and South America); whose stratigraphical record goes from the Cambrian to Pleistocene. More than 2,000 of them are types and figured specimens and include numerous historical specimens such as the Hinde and Parkinson specimens, published in Hinde and Parkinson’s monographs in 1883 and 1808 respectively. The NHM Porifera Collection is the best in the world for Mesozoic sponges and will be very useful to track changes through geological time in the geographical distributions of major sponge clades. This Collection covers most of the Porifera groups such as non-lithistid demosponges; lithistids; hexactinellids; calcareous; archaeocyaths; and stromatoporoids. Although non-lithistid demosponges are not normally preserved as fossils, spongin fibers may leave imprints that are found from the Cambrian until Recent. Unlike, lithistid massive skeletons are easier to preserve in the geological record. These reached their greatest dominance in the Cretaceous. The NHM has the most important collection of Cretaceous sponges in the world, with hundreds of non-lithistid demosponges and more than 10,000 lithistids, mostly from Europe and North America. These will be useful to unveil the diverging silicification levels. Hexactinellids are siliceous sponges that also spread from the Cambrian to Recent. They have been found living in both cold deep and warm shallow waters and have been defined as the oldest lineage of animals alive on earth today. The NHM Porifera Collection has almost a quarter of fossils of this group, mainly from the Mesozoic of Europe. Calcareous sponges have skeletons with spicules of calcium carbonate that have persisted, as the previous groups, from the Cambrian to Recent and have the biggest diversification in the Cretaceous. Their Mesozoic representation highlights in the NHM Porifera Collection and represents the third biggest group of sponges. Most of them are from Europe, but there are representatives from Asia, South America and the Middle East as well. Archaeocyaths characterize the first substantial diversification of the phylum Porifera, to which they are now generally assigned as a distinct Porifera class. They flourished in carbonate shelf and reef environments of the early Cambrian and a depauperate stock persisted into the late Cambrian. The Archaeocytha Collection at the NHM contains more than 600 specimens, mainly from Antarctica, Australia, Canada, Morocco, Sardinia, Siberia, Spain and USA. This is one of the richest and most important Archaeocyatha Collections in the world, including a mixture of over 100 cavity slides and thin sections. About a hundred type and figured specimens are present among these specimens (such as Hill, 1965 and Debrenne, 1966). The extinct class of non-spiculate poriferans Stromatoporoidea appeared for first time in the Middle Ordovician and became abundant and widespread through Silurian and Devonian until they disappeared in the Cretaceous. The NHM Porifera Collection has more than 7000 specimens and contains the most outstanding Silurian stromatoporoids such as the historical Nicholson Collection (1885-1892) on British stromatoporoids.