Minecraft wiki entry for Entity, associated text: Entities cannot pass through solid blocks, excluding vexes. Most types of entities prevent blocks from being placed in the space they occupy, except for resources (dropped items) and experience orbs, which are automatically pushed out of the block to open air. If a solid block enters an entity's space, such as falling sand or a swinging door, then it is free to move out of the solid block but not back in. For example, if a door is closed on you, you can jump up and stand on top of the bottom-half door block, if there is air above the door.