There are now different types of skeletons in Sea of Thieves:
Bone Skeletions
These are your standard skeletons that have been in the game since Alpha.
Attack with: Anything
Invulnerable: Nothing
Heals: Eating bananas
Plant Skeletons
These skeletons are covered in leaves, flowers, and the like.
Attack with: Swords
Invulnerable to: Guns
Heals with: Water
Gold Skeletons
These are gold-plated and have bits of treasure embedded within them.
Attack with: Guns
Invulnerable to: Anything until they rust
Weakness: Use water to rust them
Shadow Skeletons
These are ghost-like with beady, glowing eyes, until revealed.
Attack with: Anything
Invulnerable to: Anything until revealed
Weakness: Use the lantern raised high (using 
) to reveal them