Bones got worse with time with the whole,
Hodgins: Well, I pulled a microscopic piece of pollen that was on the victims shoe lace. I ran the superspectrofrotometryscope on the same and discovered that the piece of pollen wasn't fresh, but was digested by an earthworm plotus most rarous that is only found in a small patch of Virginia.
Bones: Good jo....
Hodgins: But there is more! That earthworm wasn't the first to eat the pollen. The earthworm at the piece of pollen while going through the soil. The soil was a composite of topsoil and cow dung. A cow ingested the pollen and excreted it into the ground. I found traces of a particle that is used in a particular brand of rendered cow food that is only sold at one store at the corner of Main and First in a small town in Virginia.
Bones: Incred....
Hodgins: On a hunch I ran the samples through the WhoozyWhazzit machine and determine the food was purchased on sale back in January 17, 1983 by a man named John Williamton. *pulls up picture*
Bones: Wow... and he is a perfect match based on the rendering of the killer's face Angela did based on the reflection she saw of the killer in the victim's eyes.
The rare whatsit that if found only in a tiny area and is the essential clue, is a common plot element in all science oriented crime mysteries. It probably started with Sherlock Holmes.
There is an ITV series, based on books of the same name, "Brother Cadfael", who is a medieval monk and herbologist. His intimate knowledge of rare plant species and the half acre of Britain where it grows is often essential to solving the crime.
Of all the standard crime genre formulas, this maybe the most formulaic of all.