The axon and dendrites are filaments that extrude from it. Abrasive flow machining was first patented by the Extrude Hone Corporation in 1970. Most consumer-level 3D printers extrude plastic layer by layer to create a 3D object. Santoprene TPV is easy to extrude into single and complex profiles. At higher temperatures tellurium is sufficiently plastic to extrude. Enzymatic activity and turgor pressure act to weaken and extrude the cell wall. Some insect larvae (including silkworms) extrude silk to make a protective cocoon for their metamorphosis. They then extrude their feeding tentacles, ready to withdraw at any hint of danger. Normally-commensal bacteria can harm the host if they extrude from the intestinal tract. When disturbed, sea apples, like other holothuroids, can violently extrude their entrails from both ends. Among amphibians, some salamanders can extrude sharp venom-tipped ribs. "pgp-2" which are effectively able to extrude intracellular pyocyanin in an energy dependent manner. It can also extrude small, simple items from itself (such as a pair of sunglasses).