1. What would happen if a person fell into a black hole?
2. Why it takes more genes to make a tomato than a human.
3. How the placebo effect works.
Limestone is composed largely of the minerals calcite or aragonite. Some limestones do not consist of grains and are formed by the chemical precipitation of calcite or aragonite. This is how limestone can be classified as chemical.
Just to add on over time they have develiped a tuff outer layer to stop weather and insects from harming them.
