system
Given the following post, respond as if you're commenting on Reddit:
human
What kinds of regular shapes will perfectly tile a sphere?
gpt
If you allow multiple shapes, the possibilities really are limitless, but if you want to use only a single shape, there is a simply mathematical property which helps understand what you can do. 

Any way you tessellate will require a corner where at least three edges come together.  Of course, on a flat surface, the sum of the angles where they come together have to add up to 360. When you are making a 3D shape, you'll need it to be less than 360 degrees, because they aren't lying flat. Well, a hexagon has interior angles of 120 degrees, and 3\*120 = 360. Thus, you can't possibly tessellate a 3D sphere with a hexagon- it must be with shapes of 5 sides or fewer.