Answer:
Eletromagnetic radiation which is also known as visible light.
Explanation:
Fossil fuels like coal, natural gas and oil.
Hopes this helps!
They have thick body coverings
I'm not sure what the alien Theory says or if there really is such a theory. If the theory says that aliens definitely exist and that they have visited Earth in the past then the theory is totally and completely without any kind of support. It's not scientific in any way because there is no evidence for such a claim. It may be thought to be probable but no solid evidence has ever been presented.
Answer: The answer is density
