So the Dead Bones have been deactivated for about 10 updates now... Here's my suggestion for what they should do.
They should spawn under the deck of the ship, and only in water. There should be about 5 - 10 of them, and 3 different types:
Sailors, with 12 health, helmets (any type) for armor and a fishing rod or a Nautilus Shell for a weapon (or a Megalodon tooth when that guy is added).
Warriors, with 15 health, a chain chestplate for armor, and Javelins or stone swords for weapons.
Passengers, with 10 health, and no armor or weapon except for a random misc item (book, stick, flower, etc).
When you first board the ship and meet them, they should be slow-moving and neutral, not caring about you, and they shouldn't be able to step outside the ship (I don't know if that's actually possible to code). If attacked, they should act like a zombie. When you reach the very back of the ship, there should be a special underwater chest behind an open iron door, with a Ruined Book inside. The book should have many torn out pages, but the last page should read some variation of this old text:
They were sailors, warriors or passengers before the ship was sunk by the green monster/black phantom/giant grey demon. Now they are just some dead bones standing there with silence. What...? You say they turned around...?
As soon as the last page is opened, there should be a chat message saying: "You feel a chill going down your back." Every Dead Bones in the ship should now be hostile to you. They should act more like a zombie pigman now, sprinting and attacking you from further away. If they kill you, they'll go back to being neutral and slow. They should drop bones, skulls, and a 50% of dropping whatever they're holding when killed.
I don't know if the book is the best idea, but there should be some way to piss them off. Fin.
Example of a power that when under water, whatever you attack then starts to drown and needs to go up for air, and if out of water it could make like a sonar blast that pushes all things in the blast back