Sponge or Algae? Please help ID

kkelly007 · Sep 9, 2020

Tank is 4 months old and parameters are as follows: 1.024 salinity; 453 Ca; 1340 Mg; 9.1 dKH; 8.3 pH; 2 nitrate; 0.05 phosphate. I currently have two clowns and three lyretail anthias, two cleaner shrimp (one fire and one scarlet cleaner), 3 blue legged hermits, 4 scarlet hermits, and a variety of LPS and SPS. All corals and fish seem to be thriving. Recently, I have had bubble-like growths on my rock structure. Can anyone please help me ID whether this is a sponge or some form of algae? If algae, will a emerald crab help, and/or is there some other critter or fish that will eat it? Pic was taken under 100% white lights. Thank you!