Digester (CR 6)

Medium Magical Beast
Alignment: Always neutral
Initiative: +6 (+2 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., low-light vision, Listen +6, and Spot +6

AC: 17 (+2 Dex, +5 natural), touch 12, flat-footed 15
Hit Dice: 8d10+24 (68 hp)
Fort +9, Ref +10, Will +3
Speed: 60 ft.
Space: 5 ft./5 ft.
Base Attack +8; Grapple +11
Attack: Claw +11 melee
Full Attack: Claw +11 melee
Damage: Claw 1d8+4
Special Attacks/Actions: Acid spray
Abilities: Str 17, Dex 15, Con 17, Int 2, Wis 12, Cha 10
Special Qualities: acid immunity
Feats: Alertness; Improved Initiative; Lightning Reflexes
Skills: Hide +9, Jump +21, Listen +6, and Spot +6
Advancement: 9-12 HD (Medium-size); 13-24 HD (Large)
Climate/Terrain: Warm forests
Organization: Solitary or pack (3-6)
Treasure/Possessions: None

Source: Monster Manual

Acid Spray (Ex): A digester can spray acid in a cone 20 feet long, dealing 4d8 points of damage to everything in the area. Once a digester uses this ability it can't use it again until 1d4 rounds later. The creature can also produce a concentrated stream of acid that deals 8d8 points of damage to a single target within 5 feet. In either case, a successful Reflex save (DC 17) halves the damage.

Skills: The digester's coloration gives it a +4 racial bonus to Hide checks It also has a +4 racial bonus to Jump checks.

A digester is a hunting and eating machine. When it is not hungry (which is rarely), it lies low and avoids most other creatures. When hunting, it looks about for a likely target, then charges forth and delivers a gout of acid. If the initial attack is insufficient to kill the prey, the digester attacks with its hind feet until it can spray acid again.