Stone Demon is an Enemy in Dark Souls.
A small floating Dragon-shaped gargoyle made of stone found in the Demon Ruins and Lost Izalith. It has a large belly and lacks legs, floating or rolling towards you instead. They will occasionally pose as statues in the scenery, but drop off their ledge when you aggro them.
They attack with a fire breath, which comes in two flavors: a stationary one (easily siderolled) and a sweeping one (easily backstepped). These demons are easy to handle individually or in small groups as every attack landed stuns them and interrupts their attacks. Be wary in large groups as several of them firing off their attack can quickly drain your health. They are quite resistant to lightning
Compared to the other enemies you will be facing in the Demon Ruins, the Capra Demons and Taurus Demons, Stone Demons are a piece of cake. They have low health, are easily stun-locked, and have a highly predictable attack pattern; simply wait for their flame attack, sidestep, and punch through their measly HP. Note that they are highly resistant to both fire and lightning.