Underground-dwelling trolls with calcified rock-like exoskin

Rock Trolls are cousins of the troll family that prefer to live underground. They can, however, sometimes be found outdoors. A rock troll attacks with two claws and a bite. It can attack 3 different opponents at once, although it prefers to focus on one target at a time. Having lived underground for so long, rock trolls have developed a calcified exoskin that looks and feels like rock. As such only blunt weapons, such as maces, clubs, and hammers will do full damage. If struck by an edged weapon, they will only take at the most 1-2 points of damage, Strength bonus notwithstanding. They will take further damage if magic edged weapons are used (the magical bonus). When a rock troll disintegrates, and the detritus is investigated, it will be found that some of its rock-like composition may have been made up of valuable gems (Treasure type L).