 In the past, a contact pheromone was assumed to be responsible for the aggregation and arrestment behaviour observed in Zygentoma.It was later found out that the aggregation behaviour is not triggered by pheromones, but by an endosymbiotic fungus, "Mycotypha microspora" (Mycotyphaceae), and an endosymbiotic bacterium, "Enterobacter cloacae" (Enterobacteriaceae), both present in the faeces of the firebrat, "Thermobia domestica".It was also shown that firebrats detect the presence of "E. cloacae" based on its external glycocalyx of polysaccharides, most likely based on its D-glucose component.