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.
A wallaby is a marsupial. The only monotremes, or egg-laying mammals, are the platypus and the echidna.
Elephants are placental mammals.
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.
No. The platypus is an Australian monotreme. The platypus is found nowhere else in the world apart from Australia. However, it is not a marsupial, as marsupials give both to live young. The platypus is classified as a monotreme because it is a mammal that lays eggs.
The platypus is not a marsupial: it is a monotreme, which is an egg-laying mammal. Marsupials give birth to live young, and do not lay eggs. The other monotreme, or egg-laying mammal, is the echidna.