Returning to monotremes, and why I couldn't guess its meaning from my small stock of Latin and Greek roots.. '-treme' didn't ring any bells.
So I googled the etymology and I rather wish I hadn't, TMI about the rear end of Puggling & Co😟
monotreme(n.)
"animal of the lowest order of mammals," native to Australia and New Zealand, which have one opening for the genital, urinary, and digestive organs, 1833, from Monotremata, the order name, Modern Latin, neuter plural of monotrematus, from Greek monos "single, alone" (see mono-) + stem of trēma "perforation, hole, opening; eye of a needle, dot on dice," related to tetrainein "to bore through, perforate" (from PIE root *tere- (1) "to rub, turn"). Related: Monotrematous
I also think 'animal of the lowest order of mammals' would make a great insult in a play
'Have at you sir! you are an animal of the lowest order of mammals and you shall feel the sting of my blade!' ! En garde! 😁