High Quality Content by WIKIPEDIA articles! Siphonia ("Siphon") was a genus of extinct hallirhoid demosponges of the Upper Cretaceous. They lived in the Western Tethys Ocean, in what is now Europe. They all had distinctive pear-shaped bodies that were attached to the seafloor via a long stem. Their common name, "tulip sponges," refers to their suggestive shape, while the genus name refers to how the spongocoel (the main tube of the sponge body) runs almost the entire length of the sponge, as though it were almost a drinking straw. The length was around half an inch (1 centimeter).