Whats the benefit of using aragonite crushed coral?

[MAK1992]

Ive been wondering for quite a while what exactly does having an aragonite crushed Coral substrate do? Im not using any if you are wondering, instead im just using sand. Just that i had seen them at a petstore with stuff written such as: helps mainting PH, Calcium, Magnesium etc. Not sure if any of that is true but if someone has used any do tell me about the benefis and if it really helps.