Neither. A scallop isn't a mammal or even a vertebrate. It is a bivalve mollusc.
A wallaroo is a marsupial.
No, they are a marsupial and not a monotreme. There are only 2 members in the monotreme category which are the echidna and the platypus.
The platypus is a monotreme mammal.
Placental.
Elephants are placental mammals.
A wallaby is a marsupial. The only monotremes, or egg-laying mammals, are the platypus and the echidna.
No. A possum is a marsupial. The only monotremes are the platypus and the echidna.
its a fish
No. An opossum is a marsupial. There are just three species of monotreme: the platypus, the short-beaked echidna and the long-beaked echidna.
The koala is a marsupial. Monotremes are egg-laying mammals, and koalas do not lay eggs, but give birth to live young.
The aardvark is a placental mammal.
A cow is a placental mammal.