What are these white strands growing everywhere?

does anything extend from them? they look like the tiny feather duster tubes i get in my tank

Sponges. I have them too. Harmless.

Nothing extends out from them. I take them out with tweezers and they feel kind of like sponge but I con't find anything online to tel me exactly what they are. Water parameters are excellent, no nit, no phos, etc.. I keep mag at 1350, calc at 425 alk at 10, and ph is 8.2-8.3 depending on the time of day. I have a fuge on the back of the tank running reverse cycle with chaeto. Lights are on 10 hours, and i run chem pure elite, puragen and filter floss in the overflow. The SPS I have in the tank are actually doing great and I thought sponges needed more nutriants in the water to do well.

just a sponge =)