Found in some live rock from Puerto rico.
A live peanut worm, several dead ones, and two unknowns:
Attached to a rock, about two inches high and one and a half inches wide. Green, looks like a leafless shrub. Resembles fern coral. The branches appear to be hollow. It is pliant, like a plant.
The second creature, three of them. The size of a raisin, dark in color, living in holes of the rock. What part I can see is relatively smooth. Under red light at light, fans rather like feather dusters appear. I believe the fans are light colored, but of course I can't tell under red LEDs.
The hermit crabs tried to get them, and they withdrew into their holes.