Skeletons are weak enemies that randomly appear in all areas that spawn bone piles.
While inactive, they are indistinguishable from the harmless piles of bones that may also be found, but will rise if a Spelunker approaches one of them to within three tiles horizontally and downwards or two tiles upwards.[confirm] Skeletons that have been awoken will revert to their inactive state if they wander too far from the Spelunker or fall into a single tile wide hole. [confirm]
Skeletons are 'blind' and will always walk directly forwards, regardless of their surroundings. They will walk off ledges and only change direction when they reach a wall. Because Skeletons cannot jump, this behavior often leads to them getting trapped in pits.
It is prudent to always treat piles of bones as if they were Skeletons so as never to be caught by surprise. Undead Skeletons lying in wait can easily be dealt with by either jumping onto bone piles, which kills the Skeleton the instant it rises, or by approaching slowly.
Skeletons are still easy to defeat using the whip or a jump once they have risen, and it may even be valuable to do so thanks to the skull they drop, which can be used to trigger traps or damage other enemies.
It is worth noting that Skeletons do not give off blood when they die, and thus do not fill the Kapala.
Within the Jungle special caution must be taken as they can be almost invisible depending on the terrain on which they spawn.