@SupaChupacabra: ...rockEt?

They should just buy a copy of Supper Scribblenauts.

@The5thElephant: When sound waves change speed when entering a different type of material they don't increase in energy.

@Neutral English Bro: Counting cash isn't something we all do everyday either, that's what butlers and accountants are for ;P

@Neutral English Bro: Fluid dynamics use extremely complex math, and is part of what meteorologists use to predict the weather.

@The5thElephant: They would accelerate if they moved towards the center, but since accelerating requires an energy input and they have no way of obtaining more energy this is impossible thanks to the 2nd law of thermodynamics.

@beaker: Supernatural creatures are just that: Supernatural.

@TheDarkWayne: Yes, in the Norwegian versions of the fairy tales the skin on their backs are composed out of bark. The "hollowed back" is more of a Swedish thing.

@TheDarkWayne: Imagine a hollow tree with a hole that allows you to see the inside of it, then imagine it looks like a person on the outside while still looking like the hollowed out tree on the inside.

@trimeta: Ohh! That's a neat illusion.

@00711: And of course in a sci-fi novel you'd have a secret society of master assassins that have figured out every single bug in the human brains visual processing methods.

Atomic Rocket has a nice list of alternative biochemistries that are theoretically possible:

@Roddy: Why choose when we can have both?

@Mrugby08: Unless you are like me and live in one of those horrible countries with universal health care.

He got a shotgun instead of a bow?

I didn't know Animal Crossing was called Animal Forest in Japan. Learn something new everyday lol.

@Bant: Electric Burger: You are barking up the wrong tree there pal. Notion Ink didn't actually have a booth at this years CES.

@Mariko13: You are barking up the wrong tree there pal. Notion Ink didn't actually have a booth at this years CES.

@goodwood8: But Notion Ink did not actually have a booth at this years CES.

@Craig Michael Ranapia: Don't forget the Xenomorphs love of Traumatic Insemination!