When a unit is croaked in combat, it leaves behind a corpse, or material remains. These remains last until its side's next turn, at which point it unpops. Until the point of unpopping, its corpse may be claimed for a trophy, Uncroaked or Decrypted.
A corpse is also left behind for the duration of a turn if the unit is harvested.
The corpse of an eligible unit killed in combat can be harvested for rations