Recently bought a reef cleaner pack with a bunch of snails and small hermits. Lo and behold a couple of days later, these white dots start showing up on the overflow. Then, they seem to multiply. They don't seem to move, but then how do they get there? I plucked a couple out and they don't look to be animals, but I can't be totally sure. Looks like little bits of smooth raised calcium to me. What is it? And should I be actively plucking them out?