The creature is alternatively named "Jack" and "The Thing with the Legs on the Path to the place where the Thing with the Quivering Jaw is"
Overview
Vomiting Diglett is a huge monochromatic monster that can be found in the path between White Desert B and the place of The Thing with the Quivering Jaw.
Its right eye looks like it is being torn out and it is vomiting some white juice across the path. It has two legs and its bottom looks like it is sticking on the ground or grows on the ground.
Pressing the up key from the path will make the screen scroll up to see its full appearance.
Speculations
It is possible that it represents a man's ejaculating penis due to its appearance, as for when Madotsuki enters the entrance that looks like a man's head, it could represent what Madotsuki was thinking about men's minds when they were looking at her which is linked with sex, and come out from a nose bleeding Buddha which could be considered to be Kenja Time (賢者タイム, Sage Time, mean after ejaculation), causing Madotsuki to meet with her deepest memory of anger as the Thing with the Quivering Jaw.