tiny black specks

Hi guys, I have noticed a few salt crystals or something of the sort and I was trying to figure out what they were when I noticed one had tons of tiny black dots on it. I pulled it out of the tank and then put it in a scope and it looks like maybe they are tiny black tube worms or something. I...

Still having a lot of tiny black specks on my sand bed the last week (see pictures). The water parameters are in line (Nitrate 4 ppm, Nittrite 0.004, Phosphate 0.02, KH 8.1, Ammonia 0 and PH at 8,4) I have 2 clownfishes, 2 x snails, 2 x Buccinulum Corneum and 1 hermit crab. All are doing...