needhelp

Does anyone know what this is? I found this worm just sitting out on the open on a frag tile in the frag tank. Their is now sand and zero live rock. It could have been introduced on a frag plug but I dip everything before it enters this tank. I’m just confused on how I’m just now seeing this...

Over the last few days my corals (predominantly LPS tank) have looked a little jaded. Hammers & frogspawns aren’t opening up. Chalices looking rather ‘close to the bone’ and a lot of ‘mouths’ are staying open. All in all nothing is opening as it should. Water params seem okay, Salinity: 1.24...