Lordy, the ear was fiddly.
From the part where the challenge was issued, I stayed low-poly for most of the modelling, only adding verts with the Knife tool where needed - being sure to keep my topology to just quads.
Afterwards, I added the subdiv surf modifier while holding my breath and… it looked great! Minimal/no shrinkage and my blocky ear became a fairly close approximation of an actual ear! Yay! Here’s the result. Obviously not attached yet, and therefore clipping with the rest of the head.
