Designating an irregular sponge spicule formed by the deposition of additional siliceous material on a rod-shaped core, and a type of lithistid sponge (formerly constituting a group Rhabdocrepida) characterized by such spicules.
Origin
Late 19th century; earliest use found in William Sollas (1849–1936), geologist and anthropologist. From rhabdo- + ancient Greek κρηπίς foundation + -id.