Darkmantle (CR 1)

Small Magical Beast
Alignment: Always neutral
Initiative: +4 (Improved Initiative); Senses: blindsight 90 ft., Listen +5*, and Spot +5*

AC: 17 (+1 size, +6 natural), touch 11, flat-footed 17
Hit Dice: 1d10+1 (6 hp)
Fort +3, Ref +2, Will +0
Speed: 20 ft., fly 30 ft. (poor)
Space: 5 ft./5 ft.
Base Attack +1; Grapple +0
Attack: Slam +5 melee
Full Attack: Slam +5 melee
Damage: Slam 1d4+4
Special Attacks/Actions: Darkness, improved grab, constrict 1d4+4
Abilities: Str 16, Dex 10, Con 13, Int 2, Wis 10, Cha 10
Special Qualities:
Feats: Improved Initiative
Skills: Hide +10, Listen +5*, and Spot +5*
Advancement: 2-3 HD (Small)
Climate/Terrain: Any underground
Organization: Solitary, pair, clutch (3-9), or swarm (6-15)
Treasure/Possessions: none

Source: Monster Manual

Darkness (Su): Once per day a darkmantle can cause darkness as the spell cast by a 5th-level sorcerer. It most often uses this ability just before attacking.

Improved Grab (Ex): To use this ability, the darkmantle must hit with its slam attack. If it gets a hold, it can constrict.

Constrict (Ex): A darkmantle deals 4d4+4 damage with a successful grapple check.

Blindsight: A darkmantle can "see" by emitting high-frequency sounds, inaudible to most other creatures, that allows it to ascertain objects and creatures within 90 feet. A silence spell negates this and effectively blinds the darkmantle.

Skills: A darkmantle receives a +4 racial bonus to listen checks. This bonus is lost if its blindsight is negated. The creature's variable coloration gives it a +4 racial bonus to Hide checks.

A darkmantle attacks by dropping onto its prey and wrapping its tentacles around the opponent's head. Once attached, it squeezes and tries to suffocate the foe. A darkmantle that misses its initial attack often flies up and tries to drop on the opponent again.