According to Wikipedia "a tessellation is the tiling of a plane using one or more geometric shapes, called tiles, with no overlaps and no gaps"
M.C. Escher was very famous (among other things) for his tessallations using animals like fish and birds. janukke, a lovely lady at Ravelry, did come up with a knitting pattern (for an afghan) for the fish tessallation a while ago, and finally I gave it a shot and knitted one of the fishies. And another one. And then another one. I'm now at number 6 and can at least lay out the first of the hexagons.
On the sewing front I've put this little etui together using braided stripes for the outside.