Centipede

Question
I don't think it is a big issue but I thought I would ask. We have what looks like a centipede that lives in one of our live rocks. Couple inches long not very big in diameter. Is this an ok thing to have in the tank with fish.
Also after a week or so I get a little algae on the glass and was wondering besides cleaning the glass is there an additive I can add to the saltwater that would help reduce it.
Thanks
Patrick

Answer
THE CREATURE YOU SAW IS A BRISTLE WORM. NOT BAD UNLESS THEY MULTIPLY TO THE POINT OF GETTING OUT OF HAND. THEY EAT WASTE FOOD. THE ALGAE IS A RESULT OF THE LIGHT AND NITRATE CONTENT IN THE WATER. USE YOUR LIGHT ABOUT 8 HOURS A DAY AND DO A WATER TEST FOR NITRATE. YOU HAVE TO DO WATER CHANGES TO LOWER NITRATE.