Unknown fruit

The porous surface of the shell of an unknown fruit, washed by the ocean, now rolls across the sand washed by the waves. Its spiky horns allow it to avoid being quickly caught and eaten, but as soon as it lands in a child's small fingers, the attempt to open it will begin. Grandma will open the hard-to-tear shell, and the fruit will fall out, smiling at everyone for a moment before being eaten.