Poecilosclerid sponges are the most diverse group of sponges, with thousands of species ranging from deep ocean to shallow shoreline habitats. Most poecilosclerids share a skeletal feature found in no other sponges. Many of their spicules (tiny, mineralized rods that make up their skeleton) have shovel or hook-like structures on the ends. These anchors (chelae) are scattered throughout their spongy body tissue, making it more rigid. The function of the shovel end is still unknown in most poecilosclerids. However, some poeciliosclerids are carnivorous (rare for a sponge), and their chelae stick out all over their body like a layer of Velcro. Small prey, such as tiny crustacenas, get snagged on the hooked ends. Sponge scientists (spongologists) wonder whether all poeciliosclerids had a carnivorous ancestor with chelae.