got a rare critter stone - what should I hunt and upgrade?

[Scottv]

title says it all thanks!

[Sellys]

Bunnies are pretty useful.

[Liopleurodon]

yep, a speedy rabbit if you've got one. Snails are also popular but not quite as versatile as rabbits. Squirrels are gaining in popularity too. All else fails, take a look through your pet journal & see if you have any pets that can't be traded or tamed. Those are usually my #1 priority for upgrades, because there's absolutely no way to get a better one.

[Awq]

Tough one. You could upgrade your Perky Pug.
Else you could try trading it in /2. Your Teroclaw Hatchling (Flying Stone) or your Feline Familiar (Beast Stone) would be nice upgrades!

[FuxieDK]

Upgrades should be saved for pets, where they don't exist as rare (e.g. achievements, professions etc)..
However, using it on a super rare wild pet (Minfernal, Unborn Val'kyr, Giraffe Calf, Ironclaw Scuttler, Shadow Sporebat and a few more) is perfectly understandable..