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Question
QUESTION: Hey, I have a 30gal tank with some coral and 2 small fish, a couple of crabs and a few snails. Now I see this tentacle type thing sticking out of part of my live rock when I feed the fish. Looks like a worm, 2 inches long but it has a serrated body. Moves in and out of the rock when something goes by it. Any thoughts?

ANSWER: Hi Brad. Sounds like you may have a eunicid or rock worm living in your rock. These are the most frequently found worms living with in the rocks in a tank. These worms are mostly omnivores and live off of detritus in your tank. They are harmless scavengers and may be beneficial to your tank because they will help clean up uneaten food and waste matter in areas that you can't reach to clean. Some species can get very large(I'm talking feet not inches) and be very difficult to remove from your tank. Hopefully you have one of the smaller species! I've heard some stories about these larger worms that could make excellent horror movies! Most of them stay small however. Do some research to first see if this is the worm you described and two to find out what species you may have.

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QUESTION: Looked at some photos of the eunicad. Perhaps this is just a baby. This one is in the same piece of rock. do they move around the tank?

Answer
Hello again. Typically they live in a tunnel network with in the rocks. If feeding is good in one particular spot you may see them more frequently in that spot. Most likely it comes out of the rocks in other spots as well, however its network openings may be located in places that are out of your view. check out this website. It has a whole bunch of pictures of worms that are most commonly found hitch hiking into your tank. Maybe this is not the worm you have. There are thousands of worms found in the ocean this site will at least give you an idea of what you have. Remember you may not see an exact match but look for similar body shape and structure and behaviors. Don't look so much at colors.
http://www.chucksaddiction.com/hitchworms.html