Platypuses

Platypuses (also known as duck-billed platypuses) are the semiaquatic egg-laying mammals that are found only in Australia, which are one of the 4 monotremes, the mammals that lay eggs instead of giving birth.

Mr. Platypus is the only platypus that appeared in the 64 Zoo Lane Universe (unless you count the other 2 seen in the audience at Wally's concert in The Story of Joey's Camping Trip).