Its name can be based on its shape, color, and purpose.
1. Shape: The shape of walnuts is similar to some leaves. You can consider naming it "elliptical leaf", "round leaf", etc.
2. Color: The color of walnuts when mature is usually dark green or brown. You can consider naming them "emerald", "brown jade", etc.
3. Purpose: Both walnuts and leaves can be used for specific purposes. You can consider naming them "practical leaves", "craft leaves", etc.