"It is the embryo of a Murnoo often called a 'sex-animal.' The Murnoo is a very important part of the Ziello race, but it isn't a Ziello."
"The Murnoo grows very fast, and as soon as it releases the teat in the male's pouch it is born--a tiny furry helpless creature who requires care at first, but grows very fast."
"In only about three years it is full grown, but it doesn't look much like its Ziello father and mother. It's much shorter, with a rounded face and ears, rudimentary upper arms, and a short tail."
"Well, as a sex-animal it turned out a strange cream shade, quite lovely, with red ears and paws."
"They look partly like Ziellos and partly like big rabbits."
James Tiptree Jr., Collision