[1] It forms sexual fruiting structures called perithecia that are spherical to oval in shape,[7] measuring between 70 and 150 μm in width when fully matured at 10 days.

[1][3] Chaetomium atrobrunneum has been reported from rabbit dung,[7] milled Italian rice,[9] water-damaged building materials, concrete, plaster and wallpaper.

[10] Chaetomium atrobrunneum grows more slowly at 25 °C (77 °F) than most other species of the genus,[1][3] reaching a colony diameter of 16–21 mm after 7 days incubation on Cornmeal Agar (CMA).

[11] By contrast, its growth at higher temperatures is much more rapid than many other Chaetomium species, producing colonies of approximately 41–44 mm in diameter after 7 days incubation at 42 °C (108 °F) on CMA.

This enzyme is involved in septum formation and cellular division,[14] and its inhibition by chaetoatrosin A is thought to be the mechanism underlying the antifungal effects of C. atrobrunneum culture filtrates against several medically important fungi including Cryptococcus neoformans.