Black-Spotted Feather Duster WormBranchiomma nigromaculata
The Crown is horseshoe-shaped with a distinctive pattern of little "Arrows" on the radioles (feathers). I've seen them in most environments and usually in 3-4 feet of water. Their parchment tubes hidden in crevices and under rocks. Their colors are banded shades of brown and white. I've seen solitary specimens and I've also seen areas with several dozen living in close proximity. Similar are the Shy Feather Duster worms, less common and are lavender or brown.