The Darkening Wild
But harder than stone is the flesh and bone / Of a troll that sits in the hills alone.
Trolls of all types have flesh like stone and are far stronger than Man or Elf, and stone-trolls are no exception. Smarter but less fierce than cave-trolls, stone-trolls will venture close to the settlements of Men and will eat anything, or anyone, they find.
Stone-trolls can grow as large as their troll-ish cousins, but tend to be somewhat more intelligent than many. Those that prey on civilized areas can learn Westron over time, though they speak a mongrel form of it, especially if speech helps them taunt and frighten their meals before they eat them.