In sea lilies, the cirri are the thin strands that line the animal's stalk. Among the tube blennies, a cirrus is a long growth extending from above the eye (a supraorbital cirrus) or extending below the neck-region (a nuchal cirrus).[5] In a nautilus, each of the animal's tentacles is composed of a thin flexible cirrus and the corresponding hardened and protective cirrus sheath into which the cirri may be withdrawn.[6]