barrel sponge

noun

noun

A sponge of the genus Xestospongia, especially Xestospongia testudinaria.

In making use of something as simple as a difference in water speed, barrel sponges are exploiting energy from currents and tides that ultimately derive from the gravitational pull exerted by the Moon and Sun.2012, Caspar Henderson, The Book of Barely Imagined Beings, Granta Books, published 2013, page 29:

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.