what is this?

[thecastle]

Hi! recently me and my family noticed this big purple thing in our salt water aquarium and none of us can seem to figure out what it is and i was wondering if anyone out there could tell me what it is or if it’s bad for our tank. if you know anything please let me know. anything will help! thank you

 

[dwest]

I’m unsure what that is. If it’s hard, maybe a species of coralline algae. If it’s very soft likely cyano. If it’s “spongy” maybe a sponge. I can’t imagine that it’s bad though.

Nice coralline growth In the tank.

 

[Double monti 61]

Possible ear sponge cool looking but grow quickly and overtake coral they can be trimmed with scissors.