As I've posted a lot of trilobite drawings here already, I thought it would be an interesting challenge to take up @Doctor Mud's suggestion to draw a Tumido. I've never drawn a crab before, so this was unfamiliar terrain for me. If I needed the additional challenge, I did this with a sprained thumb. After consulting a few resources, I laid it out and rendered it as usual with pencil.
Time: ~12 hours
Materials: Pencils (HB, H, some 3B), blending stumps, standard sized white paper.