The OSPD provides examples of many different four-letter worm types. 18x16x26 can be distinguished, suggesting that two four-letter words with the same geometric configuration must not be easy to find. Ouroboros worms come in numerous varieties. However, ROIL is a rectangle with sides 2,3,2,3, FOUL is a rhomboid with internal angles of 60 and 120 degrees and sides 2,2,2,2, and VIER is a rhomboid with internal angles of 60 and 120 degrees and sides 1,3,1,3. Finally, COOT is an isosceles triangle with sides of length three and a base of length 4.
Foldback worms come in more varieties than previously.
It is now time to examine the varieties of Ouroboros worms more closely. As mentioned earlier, I have excluded worms such as BY or BEVY which have lines folding back upon themselves. Two examples of the latter phenomenon are EYES and VIVA, both of which look like bow ties. These consist of two right triangles of sides 1,2,3 folded at a 45-degree angle with respect to each other along their hypotenuses. For words of five letters or more, a full taxonomy of Ouroboros worms is even more complex.