What is this? Sponge?

[LaneBrain]

Hi everyone, saw this last night while looking well after the lights were out. Can anyone help me figure out what this is?

 

[this is me]

I’m getting a lot of these as well. Especially under frogspawn/hammer base skeleton. Some are yellow like yours, some are purple, and some are reddish pink. I always chalked it up as a well established tank. As long as it doesn’t suffocate the coral, I leave it alone.