"Fascinating! They build not with bricks, but with bones!"- Mardolf the Orange
Skulkin refers collectively to the Skeletons of the Ninjago Underworld. A large number of them are found on Crux Prime, where they have set up a mining operation in the Maelstrom Quarry for the extraction of Maelstrom Ore. The undead nature of the Skulkin makes them highly resilient to conventional weaponry. All Skulkin can perform a special brand of chaotic Spinjitzu capable of inflicting massive damage; however, performing this Spinjitzu stuns the said Skeleton for several seconds. They are also highly susceptible to all forms of Spinjitzu, including the Imagination Spinjitzu taught by Neido in the Ninjago Monastery Ruins. Armed with an arsenal of Maelstrom weaponry, they have renewed their siege on the Ninjago Monastery, with the goal of reclaiming the four Golden Weapons.
The in-game Skulkin models show every variety having the signature head of Bonezai. However, the images used for Crux Prime mission briefings show every variety sporting the signature head of Chopov.
All skeletons are turned into music loving softies if they are near a smashed speaker rebuilt as a gramophone. This sweetness stops them from attacking, but not from using Spinjitzu.
Mardolf the Orange swears his new “Holographoid Skeleton Powerclutcherizer” invention can disable Skulkin by projecting holograms of attractive female Skeletons. Paradox doubts this, as the existence of Skeleton women has yet to be confirmed.
A common glitch that may affect any Skulkin in LEGO Universe is that the Skulkin's head, armor, and weapons may disappear.