In general, each coffee cherry contains two seeds (grains) inside. Each of these grains occupy one half of the sphere (or rather ovoid) that forms the cherry inside. Hence, they have a more curved part and another (the inside) almost flat very characteristic.
However, the snail grains contain only one seed.
When developing alone, this seed grows in all directions equally and therefore does not appear that flatter part that other grains have.
Sometimes, these grains take a more or less spherical shape and other times they almost begin to curl on themselves adopting the form that gives name to the 'caracolillo'.
Before it was said that it was a genetic error
There can be coffee cherries that inside can have 2 seeds as it is regularly found, one peaberry, 3 or up to 4 grains in a single cherry.
I was lucky they gave me 3 cherries, and 3 were different as you can see in the photo
