What is "gray short-tailed opossum"

n. A small opossum, ''Monodelphis domestica'', native South American rain forests, especially in Brazil, Paraguay, and Bolivia.

The gray short-tailed opossum (Monodelphis domestica) is a small South American member of the Didelphidae family of opossums. It was the first marsupial to have its genome sequenced. The opossum is used as a research model in science, and is also frequently found in the exotic pet trade. It is also known as the Brazilian opossum, rainforest opossum and in a research setting the laboratory opossum.