NICOS:
Thanks for the link re Brazils.
It's as I thought,,,,, I should have taken the shell off before planting - mind you, I only did One nut (I get hungry) !
I am assuming that, like peanuts (or Ground-nuts to be proper) you have to be careful not to cut or graze the skin on the kernel.
I believe that if you plant ground nuts with ripped skin etc, they will not grow.
That's possibly why children are encouraged to leave them in their shells also when planting (the nuts,,, not the children !).

I read a bit of the Forestry Commissions notes on growing native nut trees, but they only covered cobs & walnuts etc. They didn't mention anything about shelling (or de-shelling) them tho',,,,,,