It is based on an octopus, a cephalopod mollusk of the order Octopoda, specifically the one on Neptuna's head.
Its name is a portmanteau of "octopus," the animal it is based on, and "pet," referring to its tribe and it being owned by Neptuna.
Statistics
Classes: Hearty, Sneaky
Tribe: Pet Zombie
Trait: Amphibious
Abilities: None
Set: Token
Card description
It's slimy, beady-eyed, and it leaves ink splotches wherever it goes. Neptuna loves it all the same.
Strategies
With
Due to it having the Amphibious trait, it should almost always be played on an aquatic lane, which is generally poorly defended in the early-game. It also has high strength and a good amount of health for virtually costing 1 brain. This often means it can hit your opponent a couple times before being destroyed.
If you play this on the first turn in the form of Octo-Pult, this can do 3 guaranteed damage to the plant hero, unless you play it to block a plant.
Against
Octo-Pet can hit quite hard on the first few turns, so try to get rid of it before you take too much damage from it.
Since it is most likely going to be played on an aquatic lane, you are going to need Amphibious plants to fight it. However, Octo-Pet is capable of destroying a majority of Amphibious plants, including Template:PvZHLink, so be careful on which plant you play to deal with it. A good choice is Template:PvZHLink, as it can be played to destroy it relatively quickly on the second turn. Alternatively, tricks like Sunburn, Berry Blast, or Template:PvZHLink can destroy it. Template:PvZHLink, Hot Date, and Whipvine can also move it out of the aquatic lane if you lack Amphibious plants.
Gallery
Octo Pet's card
Octo-Pet putting part of its anchor in its mouth during its idle animation
It is the only Hearty zombie with the Amphibious trait.
It has the longest "When destroyed" animation out of any fighter in the game.
Strangely enough, the old textures of Octo-Pet also include the textures for Template:PvZHLink, which was unreleased at the time. This was removed in later updates.
On Octo-Pet's card, its eyes resemble those of most zombies in the game, but in game, its eyes resemble curved arches.
It and Impfinity Clone are the only token cards in the Sneaky class.
Coincidentally, they both have the Amphibious trait.
It and Atomic Bombegranate are the only non-legendary cards to have the legendary aura when played.
Hearty and 
Sneaky classes. It is made by Octo-Pult, Neptuna's signature superpower, but can also be transformed into by Portal Technician and Interdimensional Zombie, or Conjured by Eureka, Cosmic Yeti, and Triplication. It costs 3
to play (only when it is Bounced and as a card from Eureka or Triplication), and has 3
/2
. It has the Amphibious trait, and does not have any abilities. Its closest plant counterpart is Template:PvZH Link.
Beastly class, unless a 
Brainy hero obtains it via Portal Technician, Triplication, or Eureka, or Octo-Pult via Thinking Cap or Quasar Wizard, not to mention Cat Lady and Zookeeper.
Bullseye trait
Overshoot attack
Brainy
Crazy
Hearty
Sneaky