Endomychus coccineus is a common fungus beetle (Endomychidae) in Hungary. The species lives in deciduous forests, feeds on fungi. It can be found under barks of dead fallen trees, often in groups also together with the larvae (see the picture below!)
The image was made from 123 shots with the Mitutoyo BD Plan APO 10x microscope objective on bellows. Stacked in Zerene Stacker - PMax method. The beetle is a dead mounted specimen!