That brings up a question, though: what happens if you grapple something with a touch attack like these or a will-o-wisp? Do you take auto-damage from them? That sounds very old-school. 
Right, but only once attacked? But they're passive when undamaged. So I get the picture that a damaged one would attack when provoked and that attack an undamaged one could crack it, wake it up, and provoke it all at once. Sound right?