Croaked units leave bodies, which exist as physical objects for a short time after croaking. Bodies disappear at the start of the next turn that their side has, unless moved/claimed (e.g. uncroaked, reanimated as golems, eaten, used for something else like the teddybearskin rug and mounted gwiffon head in Parson's room)Erf-b1-p035. In the event that their side is eliminated, unclaimed bodies disappear at the next nightfall.
It may be that units with the special: Regeneration (Bogroll), may recover from Croaking, however, it is still unknown what regeneration means; it may mean they heal naturally without having to wait for the standard healing to full health at the start of their next turn.