These are digital images of trenches in a mineral made by networks of fungi. The circular feature in the picture on the right is a depression made by the formation of a terminal spore by a mycorrhizal fungus, which was linked to the roots of a maple tree under high CO2. Researcher Joe Quirk says: "These spores are characteristic of the ancient type of fungus that has associated with plant roots since plants first emerged onto the land over 400 million years ago. This is why the image is so exciting – it's good evidence this ancient fungus weathers minerals."
The width of the trenches is approximately 5 micrometers and the diameter of the circular spore is about 55 micrometers (one micrometer is one-thousandth of a millimeter).