The fan worm in the photograph (right) is possibly Bispira
volutacornis (Montagu), a second spiral of filaments is visible
just out of focus behind and to the left of the first.
The fan worms have long feeding filaments, which they deploy in
graceful spirals or cones to catch floating food particles. Generally
fan worms can retract these filaments very quickly and completely into
a tube or burrow, distinguishing them from tube anemones.