White stringy object on rock

[ReeferMadnessTX]

Noticed this white stringy stuff on the top of a rock shelf in an area with high light. Not sure if it is a critter or some type of algae or what. Any help with ID would be great. What I've seen when searching white stringy has been pineapple filer sponge but those doesn't quite look like the other photos posted.

 

[Crabs McJones]

Possibly a cluster of Sponges?

 

[ReeferMadnessTX]

I was leaning toward some invasive sponge so I decided to remove it the best I could. Will hopefully not see a bunch more pop up.