I was just playing minecraft on a 15w41b server with a friend, hiding in my trapdoor house. Finally when the sun came up, i took a stroll through the majestic plains of my world, when suddenly i noticed a skeleton in the distance. I thought "Looks like it still didn't despawn or catch fire, let's approach it". But when i came closer, it didn't despawn, nor catch fire. I was also able to give it one good whack-on-the-head with my battle-axe, and afterwards, it stopped moving completly It just stood there, looking in the distance, doing nothing. I couldn't move it, neither with water, nor letting it fall. It also didn't experience the unbareble feeling of drowning. It just floated there, in the air, didn't fall (see pictures in attachements). I thought, "it will move again when it's next night?" Nope, it's still there, and it won't move a bit. (sorry for the text, my story telling mode is on)

*Edit 1*

I jist discovered a spawner (spider) i killed the spider, and lit up the room. Suddenly all these skeletons started spawning around me. Same story, 1 time hit, nothing more. It freaked me out so hard, that i forgot to take a screenshot. I restarted the server, and all the skeletons were gone....