Jelly Scale is an S-grade pet that was released alongside with Coin Scale. It has the ability of converting coins you earn in the run (not from the Treasure or other bonuses at the end of the game) into points. Upgrading the scale will not increase the conversion rate, but rather will speed up the conversion time, making it far more efficient than its Level 1 form.
This pet, alongside with Coin Scale are the only pets that changes both coins and points for the other. Jelly Scale deducts the player's coins in favor of points, which makes it impossible for players to gain coins with this pet.
The best pet to have for Cookie's who just want to have a blast getting the highest score possible, no matter what the cost! And no matter how much you eat, the only thing that's going to get fat is your score! Nice!