The species recorded below is just one of many tens of thousands that belong in the Order Oribatida. We don’t have the knowledge to identify this to species level, although just going by its physical appearance we suspect this individual belongs to the genus Euzetes.
In general oribatids feed on dead or decaying matter (mostly vegetable or fungal but occasionally carrion). None are apparently parasitic. In the garden we tend to see these in soil / leaf litter taken from below the shrub border, rather than soil from beneath the grass areas, in other words they seem to be associated with high levels of decaying leaf litter.
Obviously these guys need high magnification (a field microscope or similar) to view them. One thing we noticed whilst viewing this species is its apparent inability to remain upright when on a petri dish / smooth surface. We can only assume at this point that these poor fellas are incredibly top heavy and that without the ability to grip the surface with their feet, just topple over. In the video below (apologies for the quality, it’s difficult to follow these guys and keep them in focus) we film one as it wanders around its soil habitat, then show it struggle on a glass surface and finally with a leaf added to the dish it was able to walk about happily. Unlike many other types of soil inverts, this species of mite seemed less bothered by the bright lights of the microscope.