n medium earth elemental 

Perception +14; darkvision, tremorsense (imprecise) 60 feet

Languages Terran

Skills Acrobatics +14, Stealth +14 (+17 in sand)

Str +5 Dex +2 Con +4 Int +0 Wis +2 Cha +1

AC  24; Fort +16, Ref +12, Will +14

HP 94; Immunities bleed, poison, paralyzed, sleep

Glass Armor When the sand sentry takes fire or lightning damage, its outer layer of sand fuses into sheets of hardened glass for 1 minute. This increases the sand sentry's AC to 26 and grants it resistance 5 to acid, cold, electricity, fire, force, piercing, and slashing damage. A sand sentry can't use earth glide while glass armor is active.

Speed 25 feet, burrow 50 feet; earth glide

Melee [>] fist +17, Damage 2d8+8 bludgeoning plus blinding sand

Earth Glide A living boulder can Burrow through earthen matter, including rock. When it does so, it moves at its full burrow Speed, leaving no tunnels or signs of its passing.

Blinding Sand When the sand sentry critically hits with a fist Strike, the target is blinded for 1 round.

Bestiary 2, page 109. Expanded in LOIL.