Pitback Star (3.5e Monster)

''The cleric's gone and fallen down a pit trap. Worse still, the ground's swallowed up around him. I hear him screaming something about acid, we better get him out... h-hey, the pit's moving!!!''

Pitback stars are creatures distantly related to Xorns. They are animalistic ambush predators which rely on creatures falling into its "pit". It is rarely surfaced and only looks like a odd colored patch of terrain, the center which a "false floor" that falls through and drops the creature into a pit. When surfaced it looks vaguely like a starfish with a bulbous flower bulb which forms a sealed pit that can seal itself shut. Between each of the starfish legs are vents which leak acid and with long barbed tentacle tongues. It can only use two of them at one time. It has no visible eyes and a rocky texture with earthtones adapted to the environment it travels through. It possesses limited shapechanging abilities similar to certain species of octopi, enabling them to blend into their environments.

Pitback stars do not speak but they understand Terran.

Combat
Pitback stars are ambush predators and let people fall in their "pit traps". If there are more than one creature in the area it will either try to fake being a normal trap or attempt to flee with its prey, hiding somewhere to digest or bringing pursuing creatures into danger.

Pitback stars still need to breath through their skin and cannot breath in the ground, which is why most say adjacent to the surface and never dive too deep except to flee.

Acid Spit : Pitback stars can spit acid from their many vents around the base of their torso out to 30 ft, dealing 1d4 points of acid damage per 2 HD. This is a ranged touch attack and an attack action.

Blind : Pitback stars have no eyes and are blind. They see through tremorsight and blindsight.

Engulf : The pitback star typically stays in place and acts as a pit trap (Search DC equal to Disguise check; DC 15 Reflex save avoids). Creatures which fall into the pitback star's pit trap drop 10 ft and take 1d6 fall damage, and the hole snaps shut closed. The creature is subject to its acid spit each round until they die or escape, and the acrid fumes force the subject to hold their breath or become sickened for as long as they remain engulfed. They can escape the pitback star's engulfing with an escape artist check or opposed grapple check. This forces the bulb open and allows them to slip free. If they are underground they may be buried, however.

If a creature is grappled by the pitback star's tentacles it can use its next grapple attempt to engulf a creature. Engulfed creatures are considered grappled, but the pitback star is not grappling. The pitback star can hold 1 Large, 4 Medium, 16 Small, 64 Tiny, or 256 Diminutive or smaller creatures inside of it at once.

Improved Grab : To use this ability, a pitback star must hit with a tentacle attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity.

Soft Stone Aura :  The surrounding 30 ft of unworked stone around a pitback star is softened as per Soften Earth and Stone. It uses this ability to burrow through stone and rock. It reverts back to normal stone or rock once it leaves the area. Any Reflex saves are DC 17, and the saving throws are Constitution based.

Skills: A pitback star has a +10 on disguise checks to appear as stone or as a pit trap.