Small black feathery fanworm-like creatures called Phoronid worms may be found near cerianthids. (Peacock anemone)
http://www.wildsingapore.com/wildfacts/worm/phoronida/phoronida.htm
Literally overshadowed by their more glamorous hosts, this tiny fluffy worm is commonly seen with cerianthids on our northern shores. Often several can be seen near one cerianthid. Very shy, the worms retract at the slightest sign of danger. There's a better chance of seeing them at night.
What are phoronid worms? Phoronid worms are unsegmented worms belonging to Phylum Phoronida. This is a small phylum with less than 20 species. They build and live inside tubes made of chitin. Phoronis australis is thus far, the only phoronid known to be encountered with cerianthids and it is found in all warm temperate to tropical coasts from the intertidal to deeper waters.
Features: Phoronis australis has a pair of feathery spiralling tentacles (diameter about 2cm). The body is long, unsegemented and worm-like. Those seen on our shores are grey or pinkish black, but elsewhere white ones are also seen. Most phoronids build a tube that is made of chitin (the same substance that insect skeletons are made of).