The Cocoon is the unit created from any morphable Zerg unit after it has begun mutating into another unit.
The Cocoon from a morphing Larva is extremely durable, with 200 hit points and 10 armor.
The Cocoon from a Ravager has 100 life and 5 armor.
The Cocoon from a Lurker has 100 life and 1 armor
When a Cocoon is created, it will be as damaged as the unit that created it, based on percentage of total life. For example, a Zergling with 85% life (30 hit points) will make a Cocoon with 85% life (43 hit points). If the Cocoon is canceled, the same conversion occurs once again, and the unit will have the same percentage of life the Cocoon had.
If the mutation is successful, the new unit will spawn with 100% life, regardless of the state the Cocoon was in. The unit is considered a brand new unit, so if effects such as Concussive Shells or Corruption are applied to the Cocoon, the new unit will not have those effects once it spawns. If the Cocoon is canceled, the effects will still be present.
All Cocoons that morph from units (i.e. from Zerglings, Ravagers, Lurkers, Corruptors, and Overlords) benefit from their respective Ground Carapace or Flyer Carapace upgrades. Cocoons from a Larva do not benefit from these upgrades.
Canceling a Cocoon from a Larva restores 100% of the invested minerals and gas but the used Larva will be killed. Canceling a Cocoon from a Zergling, Ravager, Lurker, Corruptor, or Overlord restores 75% of the invested minerals and gas.