It might look like the work of a mad scientist but the Vacanti mouse with what appears to be a human ear growing on its back is the real deal. You won't find this mouse at the circus; it was created at the University of Massachusetts in 1997. Dr. Charles Vacanti developed the mouse by putting a mold resembling the shape of a human ear onto its back
Ear Mouse - Why Do We Need Extra Ears?
Dr. Vacanti is helping researchers fine tune a technology that will let them re-grow ears and noses for people. It was a plastic surgeon who suggested growing ears on mice after seeing kids who were born with out ears or who'd had them torn off in accidents
Ear Mouse - How Does It Work?
The 'ear' mold was made from special fibers that are biodegradable, much like dissolving stitches that doctors often use. Before the mold is implanted into the back of a hairless mouse, it is covered with cow cartilage cells. Blood from the mouse helps the cartilage cells grow and eventually replace the fibers. Researchers say that the rodent could have the ear removed and still remain alive and healthy.

think they can hear better ?