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.
Step 2: Step 2: Add Detailing to Head
If you whip stitch the triangles together, they tend to look more like a round balloon than an icosahedron. Therefore, add some running stitches on each seam about 1/4 inch in from the edge to provide more definition. If you crochet the pieces together, you may not need this step.
Step 3: Step 3: Crochet the Collar and Sheath
Attach thread to the ring left open after sewing the head together. Work about 10 evenly spaced sc. Now you need to increase stitches rapidly to flare out the collar. I increased 10 stitches per round for 2 rounds, then 5 stitches for 3 rounds. Crochet around for 2 rounds. Now you need to decrease stitches. I decreased 10 stitches per round for two rounds, and another 5 stitches in the next round. Crochet around for a couple of rounds. Next, increase stitches again to form the sheath. Five increases per round for 2 rounds gave me the shape I was looking for. Finally, crochet around until the sheath is the desired length. About 30 rounds is a good length.
Step 4: Step 4: the Hexagonal Base Plate
When crocheting in the round, increases must be evenly spaced to maintain a nice circular shape. However, if you always place your increases on top of the increases from the previous round, your circle will start developing points. When you want a circle, this is not so good, but it is perfect for a hexagon. So, increase 6 stitches in the next several rounds, always placing the increases in the increases from the previous round. Repeat until the base is the desired size. My bacteriphage needed about 4 rounds. Crochet around for 1 or 2 rounds. Now you need to decrease. Place your decreases in the same locations as the increases from the previous rounds. I decreased 12 stitches in the first round, 6 stitches in the next 3 rounds, 10 stitches in the next round, and finally 5 stitches in the last round. You will need to stuff before your hole gets too small. Finally, add a PVC rod the length of the head and sheath to provide support. Sew the opening closed. Unfortunately, the hexagon shape is not very visible in the picture after the other parts are added.
Step 5: Step 5: Tail Pins
Start with a 5 sc circle. Increase to 10 sc in the next round. Crochet around for 6 rounds. Stuff and sew to the bottom of the hexagonal base plate. Try to sew at the vertices of the hexagon. You will need 6 tail pins.
Step 6: Step 6: Long Tail Fibers
I don't like crocheting small diameters in the round. So, I tend to use rectangles instead. Work eight rows of 60 sc. If you work in the back loops only every other row, the rectangle will easily fold into a long rectangular prism. Insert a length of cotton cording and a piece of wire and whip stitch closed. Sew one end closed and sew the other end onto the top side of the hexagonal base plate. you will need 6 long tail fibers.
Step 7: Step 7: Add the Filaments Which Dangle From the Collar
Filaments are present on some bacteriophage viruses and absent on others. If you would like them, work 1 row of 15 sc and sew onto collar. You will need six. Your bacteriophage is now complete.