Get the right nut
You can tell the difference between a ‘conker' – an inedible horse chestnut – and an edible chestnut by the spikes on the outer shell. Horse chestnuts have short bumpy spikes on a smooth ball-shaped fruit where you can see the surface between the spikes, whereas edible chestnuts are super prickly like little hedgehogs. Once shelled, edible chestnuts have a point, conkers don't.