Sentry Stone
Sentry Stones are odd stone golems made of several round segments, a bit like a stone caterpillar. They can fire beams of light from their eyes.
You find them in the Deep Siofra Well, in some Evergaols and in the Stone Coffin Fissure in the Realm of Shadow.
Drops
Ruin Fragment
Congealed Putrescence (Stone Coffin Fissure)
Resistances & immunities
Immune to all status effects
How to beat it
Status effects do nothing to a Sentry Stone, so bring plain damage. Stay out of the line of its eye beams and get in close to hit it.
Lore
The Ruin Fragments they drop are shards that fell from Crumbling Farum Azula, the city of the ancient dragons. The game never mentions the Sentry Stones directly, which leaves their origin a mystery.