it is very strong
Neither. They are exactly the same. Eggshell color has nothing to do with the thickness of the shell. The thickness will vary depending on health and diet and age of the hen.
strong enough to melt an eggshell
It is supposed to be like that because the hard eggshell protects it from bacteria. If its to hard that might be because of low humidity.
No. At least it shouldn't. Cola should only be strong enough to slowly corrode off rust. If the cola is strong enough to take an eggshell off, then they screwed up the recipe.
There are two ways to make an eggshell fertilizer. You can simply dry out and crush the eggshells and then bury them in the dirt around your plant (a few eggshells is all you need). Alternatively, you can boil eggshells in water, let them steep for about 8 hours, and then use the calcium-enriched water to water your plants.
hen they can kill animals
Eggshell
the strong liquids makes the egg start to crack and start to turn brown.
The design of the egg shell makes it very strong from tip to tip. You will notice a small end and a large end on a chickens egg. If you try to squeeze the egg from end to end it takes a lot of force to break it but if you use just a little pressure on the sides at the center it breaks easily.
Double yolk eggs are formed when a hen releases two yolks into the same eggshell. This can happen due to a hen's reproductive system being stimulated to release two yolks at once, or because of a genetic predisposition in certain breeds of hens.
The eggshell is porous.
Calcium The calcium for the eggshell comes from three sources - the diet, special bone called medullary bone (found in the cavity of all birds long bones) of pullets and the hens skeleton. The hen uses approximately 2.5 grams of calcium in the formation of one normal egg. When diet alone cannot supply this amount the calcium will be sourced internally.