White/red strings and clam looking thing

[amigo003]

Hello helpers!

I was given a tank with a few fish and live rock. I’ve been monitoring it and trying to set the right lighting to keep algae at bay.

As time went on I began seeing this white/red hair like stuff on the sand bed (reddish color) and on the live rocks (white ish color). Any ideas what they are? I don’t see any thing on the sides so I don’t think they are “hydroids” but I could be wrong? (Hope I’m not)

Also in this rock there lies a clam looking thing. It has what looks like a hard shell and something white under it. It moves but never leaves its spot. Any ideas? Good or bad?

I also found a few spaghetti worms (they are a thing of horror) are they safe?

See attached picture

 

[Lago]

Spaghetti worms aren't harmful, just filter feeders. So if anything they are more beneficial to your tank. As for the rest I cannot identify, but for what it's worth I also have them in my tank and never seemed to cause a problem.

 

[amigo003]

Spaghetti worms aren't harmful, just filter feeders. So if anything they are more beneficial to your tank. As for the rest I cannot identify, but for what it's worth I also have them in my tank and never seemed to cause a problem.

Well that’s a sigh of relief! Still wonder what that clam looking thing is.

 

[WheatToast]

Can you get any brighter pictures of the "clam" under white light?

 

[amigo003]

Can you get any brighter pictures of the "clam" under white light?

When I hit it with light it pulls back into that crevice. The front of it is partially open. It never really moves from that spot.

 

[EeyoreIsMySpiritAnimal]

When I hit it with light it pulls back into that crevice. The front of it is partially open. It never really moves from that spot.

I have a couple of these. Don't know the exact name but it's a harmless bivalve.