 Another instance of "A. ruber" was found in a cave in Spain.In order to sporulate under laboratory conditions, "Arachniotus ruber" is most commonly grown on freezing agar, which is a medium prepared using potatoes, agar, glucose, yeast extract, and activated carbon.As "A. ruber" grows on this medium, it will initially form white hyphae that will turn orange red and the colonies are pasty with occasional concentric rings of mycelium.