I didnt buy any starfish and this tank has been running for 4 months...do starfish just come alive on their own like this? And its only like half of a starfish lol
Asterina starfish. They often come in on live rock or with corals. They will reproduce asexually by splitting and can become a nuisance in our systems. Some people report that they eat corals, particularly zoas.
Personally, I like them and my reef has a bunch. If I have excess nutrients in my tank, the population explodes. I reduce feedings and their numbers decline.