Unknown organism

[mgutsch1]

I have a coral skeleton that I put in my tank about four months ago. Shortly after, probably like 4-6 weeks, an organism started to grow on it. I was told by the person who gave me the coral rocks that I could put them in my tank and they would grow coral. I didn’t believe her, but the rocks were pretty so I put one in there. I still have a bunch not in the tank. Anyway, it just keeps getting bigger and bigger, and I want to know if it is coral or something toxic. I have attached a picture. Thank you!

 

[tzabor10]

Looks like palythoa “roots”. I have a lot on the underside of my rocks. I’d be careful until you get a good identification