Violescent Sea-Whip

P. clavata has a branching structure forming a fan-shaped colony in a single plane. The stem and branches are stiffened by gorgonin, a complex protein that produces a horny skeleton. The coenenchyme, a thin living layer of cells, covers the skeleton, and the polyps protrude from this, each with eight feeding tentacles surrounding a central mouth. The polyps are up to 10 mm (0.4 in) high and the whole colony up to one m (3 ft) high and 1 m across. The colour is usually red, but may be partly yellow.

The violescent sea-whip is native to the coasts of Spain and Portugal in the eastern Atlantic Ocean, and to the western Mediterranean Sea. It grows on reefs with its base buried in the sediment at depths between 10 and 100 m (33 and 328 ft), but usually between 15 and 40 m (49 and 131 ft). It is considered to be an ecosystem engineer, as its presence alters the flow of water, changes sedimentation rates, and alters the distribution of nutrients, thus affecting many organisms in its vicinity.