It is an extremely long tapeworm, and can reach an enormous length up to 6–10 m. The scolex bears four large suckers, which are the holdfast organs to the host.
Moreover, one defining feature of the genus is that there are two sets of reproductive organs situated at lateral sides with the associated cirrus pouches and genital pores in each proglottid.
Once inside the intestine of mites, the eggs hatch and the oncospheres penetrate into the haemocoel and develops to the cysticercoid stage.
M. expansa infections are generally harmless and asymptomatic, even when the tapeworms are present in large numbers in young lambs.
[6] Diagnosis is done by analysis stool sample in which eggs can be detected, or often observation of the gravid proglottids in feces and anus.