Boulder Boars appear on B2F and B3F of Emerald Grove in Etrian Odyssey Untold: The Millennium Girl and first appear as giant stone formations. Some of these are not actually alive; however, the ones that are will charge all the way to the wall it's facing (or the party) in one go one turn after waking, which happens when the party walks within one or two tiles of the monster's facing direction. It is resistant to all physical attacks.