User blog comment:Look-a-troopa/Miscellaneous Witches/@comment-16075172-20140929124628

Established canon by DMS: When the witches were killed by the Ludusians, the ground that they shed blood and died on absorbed them into the environment and mirrored it in their image. This is why certain places in SR world have their environments, even though they're right next to each other. (Like, Cocytus died in the middle of what is now Snowfield, Trewinnard died in the middle of what is now the submarine series, etc.)

Also, I think that it would be better if the witches were all humand/gridmasks/Ludusians or appeared  more like it.