Not much info on this guy, which is the 3rd to last (out of 52) mobs I need for Hunter Achievement. The picture posted above implies he spawns in a dry tunnel but I have to believe they pulled him all the way there from the spot deep in the water tunnels where he seems to make his home. The location of the PHer is, I believe, 200, -327, -286, where various oozes share quarters with this mob.
Once I get the actual spawn I will confirm.