What's this on my bubble coral

[wmchaseb]

Hey guys I received this bubble coral on friday. I wanted to ask what this slimly brown looking stuff is at the base of the Skelton. First pic is right after dip, second is a few hours later in the tank.

 

[Reefer5640]

Looks like sponge, kind of hard to see it on my phone

 

[wmchaseb]

Looks like sponge, kind of hard to see it on my phone

Should I leave it be?

 

[Reefer5640]

I’d pull it off so it doesn’t start to pester the coral just to be safe. Some sponges are not a huge concern. Some can be invasive. If you decide to remove it I find it best to remove it in another container so it’s not as likely to spread.