A cocoon is a stage present in Chimeran biological development. Chimeran infection victims are often enveloped in such forms when they are delivered to a conversion center. Inside each cocoon, the human body is broken apart and recombined into a new strain of Chimera. It is theorized that multiple infected are required to breed the larger strains of Chimera.
Due to the overheating hazard that many Chimera suffer from, cocoons are often observed and cooled through external measures to prevent damage to the developing Chimera. This brings about the theory that the conversion process is not being performed in the ideal environment and it is unknown if there is a more natural way for the species to reproduce.