Behold, the Water Chinchilla!
Water Chinchilla CR 1/3XP 135
N Tiny animal
Init +2
Defense
AC 14, touch 14, flat-footed 10 (+2 Dex, +2 size)
hp 6 (1d8+2)
Fort +4, Ref -1, Will +0
Offense
Speed 30ft., swim 30ft.
Melee bite -2 (1d3-4)
Statistics
Str 3, Dex 8, Con 14, Int 2, Wis 10, Cha 14
Base Atk +1; CMB +1; CMD 7
Languages None
Ecology
Environment River
Organization solitary, cage (3-7), barrel (8-20)
Treasure none
Special Abilities
Purify Water (Su) A water chinchilla placed in any liquid will absorb up to two gallons of the liquid into their body. Once at least one gallon is absorbed in this way the water chinchilla will loose it's land speed but gain +2 natural armor due to swelling. If squeezed, any liquid inside the water chinchilla will be wringed-out, this does not harm the water chinchilla. Liquid that has passed in and out of a water chinchilla in this manner is treated as if it has had the Purify Food and Drink spell cast on it with a caster level equal to the water chinchilla's hit dice. A water chinchilla may only purify 2 gallons of liquid per day in this manner. A water chinchilla that absorbs a liquid is subject to the same negative effects that would be inflicted upon it if it drank that liquid, though it gains a +2 bonus to Fortitude saves against the effects of those liquids.
Water chinchillas are small, almost spherical creatures with gray fur. They have large rabbit like ears. When a water chinchilla touches water they absorb it and swell up like a balloon allowing them to swim around easily.
BTW, this is from
Sands of Eiklatha, a 3rd party Pathfinder setting set in a desert land. Also, water chinchillas can be sold individually or in water-filled barrels of 10.
And yes, you can get them as a familiar.