Stinky the Snail

Stinky the Snail can be purchased at Crazy Dave's shop for $3,000 after the player unlocks the Zen Garden mode, and will slowly collect coins in the main Zen Garden area as long as he is awake. He will fall asleep after three minutes, however, and you must click him to wake him up again.

Feeding Stinky the Snail Chocolate will make him go faster and keep him awake for about an hour. Chocolate is obtained randomly from zombies after Adventure Mode has been beaten at least once and Stinky has been purchased.

He is originally from the Insaniquarium game (which Zombiquarium is based off of), made by PopCap Games and Flying Bear Entertainment, in which his role is also collecting coins for the player.

Trivia

 * You can feed Stinky Chocolate while he's asleep. If you feed it to him while he's asleep, he'll wake up and get the energy from the Chocolate.