Boneses!
(Warning: links to realistic fake bones)
Babies are just put together strangely.
Trepanation is alarmingly sensible to me. I think I should be weirded out by it, but instead my reaction is, "Oh, a hole to keep pressure differentials from building up / to make it easier to clean, that makes sense!". No, you may not try it on me.
Fetuses are truly creepy.
They also have other human bits, and non-human skeletal bits. Nifty.