Is a kangaroo rat a living cell that isn't an organism?

No, a kangaroo rat is not a living cell; it is a small mammal belonging to the heteromyid family. Kangaroo rats are complete organisms, capable of independent life, with complex structures including organs and systems. In contrast, a living cell is the basic unit of life, which can be part of an organism or exist as a single-celled organism itself. Thus, a kangaroo rat represents a higher level of biological organization than a single cell.