Have you cracked a black walnut?
Or, perhaps more precisely, have you tried to crack a black walnut?
I found this half of a walnut shell on my walk this morning. The squirrel who enjoyed the nutmeat at the heart chewed through against the grain, avoiding what little help the seam between the shell halves gives. His technique doesn’t translate well to human teeth: his grow back. Instead, we use saws, hammers, and snips to get inside. But, luckily for us, people sometimes do crack these walnuts and bake them into cakes or cookies. The effort is worth it.
What persistence one must have to continue until reaching hidden delights, or what hunger.