Long Tentacles Coming From Inside Rock


New member
Hey everyone, I have a question for everyone which has puzzled me for a week or so. I bought some live rock at HOuse of Fins, Miami(great store), and a week later, some interesting things happen. At night, when most of the ambient light and the aquarium lights are off, these long tentacles come out of the rock. It has puzzled me for quite some time. They come at 5 minutes after the light is off, and retract whenever I turn the light on, which scraps my idea that they are sweeper tentacles, because their retraction is that of a brittle star. However, I have ruled out it being a brittle star, because there are no apparant tube feet, spines, and it is translucent. I then noticed that it had some sort of neural response, because it seemed to "feel " around, searching the gravel bed for whatever it needs to find.

Some other notes:
Average length - 4 inches
Average Width - 1-2 millimeters
Number of Tentacles- Rock 1(10), Rock2(10)

Heres a pic, look near the base of the rock, a little to the right.



New member
I was going to say wait til your tank has been up and running for a year and see how many of those guys you have but if you have had it for 2 years you should be seeing a lot of them already!