There is an island in the green sea on the north side of it where 5 of these things sit. 4 of them are readily visible from the north side of the sea, the 5th is not, so be careful with pulling. You will need lull/harmony or a feign-death tactic to bring just 1.
These are straight-up warrior enemies, no special resistances that I could see, do not summon. They sometimes drop advanced research componants.