Anyone what to take a stab at an ID

[corpusse]

Flatworms (Planaria) they will reproduce very quickly.

I'm pretty sure they are the orangish type that do reproduce like crazy but I'm not 100% sure. There are some more harmless kinds that don't end up taking over a tank.

Still I'd recommend you pick up some flatworm exit and treat your tank immediately. Better to get them now, then when you have 1000s.

The flatworms themselves are not harmful but when they die they release a toxin. A small amount won't have effect on a system but thousands will. They also become very unslightly when they cover every coral and rock.