# Fusion
Players can fuse their pets into a new pet with a different rarity level, thus fusion is one of the most important mechanics of the Pethereum metaverse. When two pets enter the fusion chamber, a new pet emerges and inherits the physical traits of parent pets but the parent pets disappear forever. Since all pets have a rarity level based on their physical traits, the result of the fusion can be a pet with better stats or lesser stats. This result is solely based on the physical traits of parent pets because a new physical trait cannot be generated with the fusion.
Calculation of fusion’s chances is simple since all the physical traits (hair, ear, eye, mouth, tail, feet, color, second color, body shape, pattern) have a rarity level and this rarity level will determine the result of the fusion. The dominance of a physical trait is based on the rarity level of the two fused parts. You can see fusion calculation below.
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