Nail with String Vanishes / Black Worm Labyrinth

I just had a really weird experience, I was looking at a wall and noticed a small nail with some sort of black tattered bit of material, could have been a string? hanging from it, not a couple of inches long. I'm really tired so I must have mistaken it for what it really was, which I can only assume to be some bizarre insect that was perched on the wall. I came to that conclusion on account of the fact that the nail with the string is no longer on the wall. I'm either really really tired or I'm losing my mind!

But prior to that bizarre disappearance, the strange black string that I previously thought that I'd seen gave me an interesting idea. It made me imagine giant black worms stuck to the side of a vast stone wall. Maybe they are slugs, vast leeches the size of semi trucks clinging to the stone with thick glue like muck that oozes down in long lines of stinking liquid. Their backsides might have strange patterns, perhaps resembling the faces of larger beasts to scare away whatever might fly up out of the surrounding space to consume them. Think of the Monster Brains logo as a good example. But I picture myself, stuck to this giant wall, attached to the sticky slimy covering of ooze from all the giant slug like creatures. I can move, I can crawl, climb up and down, but I can't let go. And on some of these giant black worms I imagine half dissolved bodies, rotting flesh and bone constructions stuck to the surface of these large beasts as their very skin consumes its meal, like a sort of quicksand with acidic digestive juices bubbling up. What is it about horse bones that creates the recipe for glue? Or animal bones used in making Jello? Perhaps these worms use the bones of their dinners in a similar fashion, excreting them in a gelatinous sticky trail. Being stuck to this wall and being surrounded by hundreds, possibly thousands of these vast horrifying creatures, tall as trucks, curling, shifting in every direction, they would appear as giant grotesque walls, become like corridors through which I must pull my way through, hoping not to get stuck to them.