Crimson mushrooms and other things like it are acting weird

Whenever i try to place a block inside new nether blocks like crimson mushrooms I expect them to be broken by the block like overworld grass, but they don't break, they act as if they have the properties of a wood block. For example placing any block on it, it gets placed outside the block similar to a torch. but here's the weir part, they float when blocks under them are broken! Also gravity affected blocks don't break it. (example png's below)