Is this a sponge on my Acan?

[JonnyTorch]

Hey guys just like the title says. My Acan has new fleshy heads all over but the other side on the skeleton this white thingy popped up, it looks like it retracts and is fleshy too, is this a sponge? The other heads are growing great, some of which are smaller than that white thing. What is this? Acan has been growing and opening up great, it's closed bc it got ticked I turned it around it for the pic.

 

[JonnyTorch]

Pretty sure it's a sponge, not sure if It's an aggressive one that will take over or not.