There's an interesting new study published in Nature Geoscience by UA geoscientist Matthew Pasek. He found that fulgurites [right. Credit, Matthew Pasek] formed by the intense heat of lightning strikes, contain unusually large amounts of phosphite, a form of phosphorus that is low in oxygen and was once common on primordial Earth . Phosphite is not common in the natural cycle today, so there are questions as to where it came from in the past, when microbes widely depended on it. It's hard to account for global quantities just from lightning, but its an intriguing newly recognized source.