Drawing of 3D shapes

I was teaching my stepson a math lesson on Attributes of Two-Dimensional Shapes when i thought of drawing something 3D. It was harder than I thought, so I stuck with shapes. I added the strands of leaves because I was already giving up on 3D and figured I would doodle and try different shading styles. Lol I was going to toss it but my fiance said it was good and I should straighten the lines and darken and lighten areas. So I did and this is how it came out.