Weird white tubes

[primoninja]

So just wondering what these tubes are. I had them before when I began my 30 gal saltwater. They disappeared when I clean up my tank, but they have come back. At the moment I am seeing them as not a pest but like more clarification. Found a longer one beneath my toadstool frag. Broke that one off and it kind of disappeared.

 

[Rjukan]

It's a type of sponge. Looks kind of like a pineapple sponge, but need clearer pics to know for sure.