Help IDing this gowth on my Frogspawn

[oldbob50]

Had this frogspawn in the tank since the middle of May. It's doing great and has doubled it's size in that time. I notice, last night, this accumulation of white stuff on one side just under the fleshy polyps. Looks like it could be a sponge but I have not seen anything else in the tank that have these tubular structures. If it's not a sponge, any guess as to what it is and is it a concern for the Frogspawn or the rest of the tank? All my water parameters are good and I am doing a small amount of sugar dosing (1/4 tsp per day)

 

[Crabs McJones]

Looks like a sponge to me. If it's not bothering the coral i'd leave it be