There are lots of things that are creepy about Zangetsu. His habits, his appearance, his very aura... but that worm thing is probably by far and away the creepiest. Eyeless and otherwise featureless, with its blunt humanoid teeth, slimy texture, and bright red inner mouth... It was an appendage with just one purpose; swallowing prey whole.

Zangetsu turns, the worm's anchor point on his body turning with him, and he merges both his arms into the worm's body to give it little more dexterity-- and so he can see what he's doing. Inside the slick innards of the worm, there's nothing to grab on to. Just warm, wet saliva and... something that kind of makes skin tingle. And not in a good way. This thing isn't meant for just holding on to prey, after all.

He sees the shadows creeping up on Tyki's legs, hears Childermass' instructions, and feels energy start to build up inside the appendage. With the last bits of his strength, Zangetsu pushes down with the worm, down, down into the shadow, like pushing a bobbing cork down beneath the surface of water.

With a loud snarl and a burst of searing black and red energy, Zangetsu slams Tyki down into the shadow, detaching the worm appendage and pulling his arms free as he does once he sees the top of Tyki's head (pushing up through the worm's body... gross) disappear into the shadow.

Luckily for Tyki, the worm (and its digestive juices) will harden, then crumble to nothing, once detached.

The memories will not crumble to nothing, however, so enjoy that.