Tullgren funnel

In biology, device used to extract mites, springtails, fly larvae, and other small invertebrates from a sample of soil.

Soil resting on a net inside a funnel is illuminated from above, so that the top layers of the soil warm and begin to dry out. The invertebrates, trying to escape the desiccating effect of the heat burrow downwards and in the process drop out of the soil and through the net, to be collected in a beaker resting below the funnel.