The Shadow IRL

[Anxt]

That thing is nasty as heck! Any information on what this actually is?

Tubifex worms which all grouped together to form one big mass of grossness. At least, that's the theory. They contract when light hits them because they are photosensitive, making it look like they are pulsing. The naturally live in slime and filth, so when necessary, they find similar habitats amongst their brethren, which are slimy and gross.