...And Water Bears, Oh My!

Tardigrades, also knows as water bears or moss piglets, are microscopic animals distantly related to arthropods. They are best known for their ability to withstand extreme environments, from boiling heat to arctic cold, even the vacuum and radiation of space. They feed by injecting their piercing mouth-parts into plants or smaller animals, then sucking out the victim's bodily fluids. They can be found in almost any environment, preferring to swim in algae-filled ponds or burrow in loose dirt as they forage.

The following monsters are based on the real-world micro-animal, with some exaggerations to their abilities for dramatic effect.

A giant water bear is a slow predator that feeds on even slower animals and plants. For an alert party, it is merely a hard-to-kill nuisance rather than a real threat. The testudo, on the other hand, is far larger and more aggressive, mindlessly biting any creature it encounters in order to determine if it is edible.

Giant Water Bear

This cat-sized creature has a segmented, barrel-shaped body with four pairs of stubby, clawed legs. Its head is dominated by a circular maw ringed by sharp teeth. Its tiny eyes are almost invisible, protected by folds of its exoskeleton.

GIANT WATER BEAR (CR 1/2)

XP 200
N Tiny vermin (aquatic)
Init +1; Senses darkvision 60 ft., tremorsense 15 ft.; Perception +0

Defense
AC 15, touch 13, flat-footed 14 (+1, Dex, +2 natural, +2 size)
hp 5 (1d8+1)
Fort +5, Ref +1, Will +0
Defensive Abilities endure elements, torpor; Immune mind-affecting effects; Resist acid 5, cold 10, fire 5

Offense
Speed 20 ft., burrow 5 ft., climb 10 ft., swim 20 ft.
Melee bite +3 (1d3-4 plus grab)
Space 2-1/2ft.; Reach 0 ft.
Special Attacks blood drain
Statistics

Str 2, Dex 12, Con 12, Int --, Wis 10, Cha 2
Base Atk +0; CMB -6 (-2 grapple); CMD 5 (17 vs. trip)
Feats Great Fortitude[B], Weapon Finesse[B]
Skills Climb +9, Swim +9
SQ amphibious
Ecology

Environment any

Organization solitary, pair, or sloth (3-6)

Treasure none

Special Abilities

Blood Drain (Ex) A tardigrade can suck blood from a grappled opponent; if it establishes or maintains a pin, it drains blood, dealing 1 point of Constitution damage.

Endure Elements (Ex) A tardigrade can withstand extremes of heat and cold without ill effect. It can survive in temperatures between -50 to 140 degrees without needing to make a Fortitude save. At temperatures outside this range, the tardigrade suffers half the normal damage for exposure. 

Torpor (Ex) If a tardigrade is rendered unconscious as a result of extreme heat or cold, starvation, dehydration, or suffocation, it takes no further damage but instead enters hibernation, becoming a dessicated husk. (Cold or fire energy attacks can also induce torpor, but continue to inflict normal damage.) A tardigrade can survive almost indefinitely in this state. If returned to a safe (non-damaging) environment and exposed to a water source of its size or larger, it rehydrates, regaining consciousness with 1 hp in 1d6 minutes.

Testudo

This creature vaguely resembles a huge, eight-legged bear fully encased in heavy plates of segmented armor. Closer inspection reveals a blunt head with few discernible features beyond a large mouth filled with piercing and sawing teeth.

TESTUDO (CR 7)

XP 1,400
N Huge vermin (aquatic)
Init -2; Senses darkvision 60 ft., tremorsense 30 ft.; Perception +0

Defense
AC 20, touch 6, flat-footed 20 (-2 Dex, +14 natural, -2 size)
hp 92 (9d8+54)
Fort +14, Ref +1, Will +3
Defensive Abilities endure elements, torpor; Immune mind-affecting effects; Resist acid 10, cold 20, fire 10

Offense
Speed 30 ft., burrow 10 ft., climb 15 ft., swim 40 ft.
Melee bite +12 (2d6+8 plus grab), 2 claws +12 (d8+8)
Space 15 ft.; Reach 10 ft.
Special Attacks blood drain
Statistics

Str 26, Dex 6, Con 22, Int --, Wis 10, Cha 2
Base Atk +6; CMB +16 (+20 grapple); CMD 24 (36 vs. trip)
Feats Great Fortitude[B]
Skills Climb +16, Swim +16
SQ amphibious
Ecology

Environment any

Organization solitary or pair

Treasure none

Special Abilities
Blood Drain (Ex) A tardigrade can suck blood from a grappled opponent; if it establishes or maintains a pin, it drains blood, dealing 1d4 points of Constitution damage.
Endure Elements (Ex) See the giant water bear description.
Torpor (Ex) See the giant water bear description.