worm in sandbed

I have these “worms” in a few spots in my 55 gal reef not sure what they are or if they are a pest or not.

I noticed these weird worms? In my tank they eat food if I put it down there. They've recently been popping up all over the tank. What are they? And are they harmful?

I was readjusting a little log we have and when I picked it up all I saw was a stomach? Part. I literally jumped back, it surprised me. Does anyone know what it is and is it safe for my fish, crabs, snails, and coral/mushroom corals? They're my main concern obviously and I just want to make sure...

I have been setting up a small NPS tank with my Fluval Evo 13.5 and recently noticed a small red object in the sand bed. At first I thought it was just a left over piece of Gracillaria or something but I took a closer look earlier because I noticed it had moved and realized it has lots of little...

Found a red slimy worm that has stringy extensions could be a spaghetti worm but never seen one red. Sifted through the sand to see if there was more and didn’t see any so far. This one found going after my torch.