Otherwise, no currently living mammals lay eggs. It is considered the ancestral state of mammals. read more
The tracts for urine, feces and sperms come straight to this cloaca and therefore these creatures are named as monotremes, meaning "one hole". All the members of the egg laying mammals list share some basic characteristics with one another. read more
The mammals that lay eggs are Platypuses (no, not platypi, platypuses) and echidnas. Those are the only extant monotremes today, if you went back a hundred million years or so you would probably find some more. read more