Okay, for now I will assume that the Tsaesci resemble humaniod snakes, with sinewy legs and powerful torsoes. I do this because nagas already exist in the Black Marsh, and so far as I can tell no one in Lore has compared the two. I gather that this is because they don't resemble each other.
If in this story they look different, I'll edit. Lemme know if anyone else has an opinion, or if I am totally forgetting that the Tsaesci were already described!
EDIT: Posted a couple sketches showing what Mum-mra looks like, more-or-less. In my... albums? I don't know how this place works.