My husband and I recently set up a 75 gallon salt water tank. It is still going through its cycling process after 3 weeks. The live rock was purchased from the Gulf of Mexico and has live plant growth, clams and some corals. Last night we noticed this "creature" and we are not sure what it is.
I have attached the best picture I was able to get. As far as I can tell it has 14 "tenacle-like" arms.