Hyalonema Lusitanicum, the Glass-rope Sponge. Half the natural size. The rush-like threads at the bottom form a twisted rope terminating in the teat-like projection at the top, where it is covered with fine sponge. This coil is the Glass-Rope. The sheath, or incrustation of little starry warts, is the work of a polyp, known as the Palythoa fatua. The conical head is a mass of sponge once called Carteria.