Axies are genetically engineered fantasy creatures created by the MEO Corporation for an as yet unknown purpose. All Axies belong to the same species, which allows them to interbreed with one another no matter how different their appearance might be, as long as they aren't direct offspring or siblings.
Although some Axies resemble mammals, every one begins its life cycle as an egg. After 24 hours, eggs automatically transform into larvae. Larva gain the ability to morph into "Petite" Axies after an additional 48 hours. The transformation from larva to petite does not begin, however, until the appropriate transaction is entered into the blockchain. A similar process is required for each Axie to reach adulthood - a 48 hour wait, followed by entering a transaction into the blockchain. Adult Axies can breed (providing they have enough Exp), battle, and participate in any other available activity.
All Axies are listed in the Axie Encyclopedia.