A delver is about 15 feet long and 10 feet wide. It weighs about 6,000 pounds.
Delvers speak Terran and Undercommon.

A delver prefers to fight from its tunnel, which it uses to protect its flanks while lashing out with its flippers.
A delver expecting trouble may honeycomb an area with tunnels, leaving most closed with layers of stone 1 or 2 inches thick.
The delver can quickly dissolve the stone cover and pop up to attack unexpectedly.
Corrosive Slime (Ex): A delver produces a mucuslike slime that contains a highly corrosive substance. The slime is particularly effective against stone. A delver?s mere touch deals 2d6 points of acid damage to organic creatures or objects. Against metallic creatures or objects, a delver?s slime deals 4d8 points of damage, and against stony creatures (including earth elementals) or objects it deals 8d10 points of damage. A slam attack by a delver leaves a patch of slime that deals 2d6 points of damage on contact and another 2d6 points of damage in each of the next 2 rounds. A large quantity (at least a quart) of water or weak acid, such as vinegar, washes off the slime. An opponent?s armor and clothing dissolve and become useless immediately unless the wearer succeeds on a DC 22 Reflex save. Weapons that strike a delver also dissolve immediately unless the wielder succeeds on a DC 22 Reflex save. A creature attacking a delver with natural weapons takes damage from its slime each time an attack hits unless the creature succeeds on a DC 22 Reflex save. These save DCs are Consitution-based.
Stone Shape (Ex): A delver can alter its slime to temporarily soften stone instead of dissolving it. Once every 10 minutes, a delver can soften and shape up to 25 cubic feet of stone, as a stone shape spell (caster level 15th).

---

System Reference Document -> List of Creatures (SRD)