A worm that looks like a feather duster
Sabellidae are a family of segmented worms which look a little something like this:
Those long feathery protrusions called branchiae are actually coming out of their head. Their purpose is to trap small particles of food which they eat. They also serve a respiratory function. Unlike most filter feeders Sabellid worms are remarkable fussy eaters and their branchiae are highly specialized for catching the right type of food. Sabellidae protect their body with tubes of hardened material like sand and bits of shells cemented together by Calcium Carbonate. They spend most of their time with only their head protruding. They can retract their head when they are threatened.
Sabellid are found in the inter-tidal zones all over the world but are more common in warm waters.