Assortment of unidentified white things

[Mcdonalds]

Three things I want to ask about. White snake like things in the back chamber of my AIO and back of the display, they have been there for a bit now, I think they are getting bigger. White hair like growth in dark spots of the tank (that I can’t get good pictures of). And finally TONS of little cactus looking white balls that are on the walls of my return pump chamber, I first spotted two large ones on a dead hermit’s shell on the sand a few months ago but ignored it as that’s what lots of people say to do, I figured it was an “ugly”. I don’t know what my alkalinity or Calcium are because I don’t have corals. Phosphates somewhere near .2, nitrates about 5.
Thanks for the help, pictures attached below.

 

[Soren]

The "cactus" things in the first photo are likely pineapple sponges. The white tubes look like small feather duster tubes or those of spirorbid worms. The white hair-like growth on rock undersides could be sponges.
All of these things are considered harmless, but can sometimes become a problem due to population explosions.

 

[LiveFreeAndReef]

Little fuzzy ones are pineapple sponges for sure

 

[Mcdonalds]

The "cactus" things in the first photo are likely pineapple sponges. The white tubes look like small feather duster tubes or those of spirorbid worms. The white hair-like growth on rock undersides could be sponges.
All of these things are considered harmless, but can sometimes become a problem due to population explosions.

Just found the pineapple sponges in another post. I would say they have exploded to that number because I just looked there like a week ago. Hair grew pretty slow. The worm things were slow as well. Now if this did cause problems, what could help?

 

[Soren]

Just found the pineapple sponges in another post. I would say they have exploded to that number because I just looked there like a week ago. Hair grew pretty slow. The worm things were slow as well. Now if this did cause problems, what could help?

I don't know what can be done with them. From what I have in my memory, most people seem to consider them harmless and just let them run their course. Populations grow when food sources are available and dissipate as the food is used up. Even in a stable system, there is still some biological fluctuation.