I bought a hershey kiss and there was peanut er in it?

iv had a hershey kiss b4 and like it was chocolate! but then! the wrpper to the hershey kiss wasent silver and shiny so i bought it cause it was perrty...i ate it and boom! there was peanut er! i think! i spat it out and made my ler try one too! how do the get peanut er in a hershey kiss if its hard chocolate?