Bacteriophages are viruses which attach bacteria. They look so cool I just had to make one for myself. In the steps below, I will give general guidelines for crocheting one of your own. Detailed steps are not given, but it really isn't that hard if you have made crochet critters before.
Step 1: Step 1: the Head
Bacteriophage heads contain the viral DNA. They are generally depicted as an icosahedron - a solid geometric figure made up of 20 triangles. There are 5 triangles whose apexes meet at the top, 10 which circle the middle (flip every other one upside down so its base is at the top), and 5 whose apexes meet at the bottom. I used equilateral triangles for the top and bottom, and isosceles triangles twice the height of the equilateral triangles for the middle. My equilateral triangles started with 14 sc for the base and decreased to 1 sc at the apex over 13 rows. My isosceles triangles also started with a base of 14 sc, but decreased over 26 rows. It is helpful to have paper patterns to follow. For the 5 triangles at the bottom of the icosahedron, stop with 2 sc remaining so there is an opening for the neck. When all pieces are crocheted, sew or crochet them together and stuff.