Which shape is for salt and which is for pepper?

I got a set of 10 mini square shakers and 10 mini round shakers for free. I was excited to put salt and pepper in them so each person at the table would have their own mini salt and pepper (for fun!)

Now I am staring at them all lined up questioning which is the salt and which is the pepper.

Additionally, they have the same amount of holes in the top (9).

So I am asking reddit, tell me which is which. Thankyou!