Bonnemaisonia hamifera

About

Bonnemaisonia hamifera is a species of red alga in the family Bonnemaisoniaceae. Originally from the Pacific Ocean, it has been introduced into the northeastern Atlantic Ocean, where it is considered invasive on European coasts. It exists in two phases which, at one time, were thought to be different species; a medium-sized feathery form attached to other seaweeds, and a small tufted form known as Trailliella.

Summary from Wikipedia