Quimera is a rare cat with a unique characteristic where each half of her face is a different color, including her eyes. While some may believe she is a chimera, which is a composite individual made up of cells from at least two different original embryos, geneticists believe that cats like Quimera are merely striking examples of calico cats. In a calico cat, one gene for fur color is located on the X chromosome, and in any female, expression of all the genes that are on the X chromosome will be 'mosaic.' This means that half of them will express one version of the gene (e.g., black fur), and half will express the other version of the gene (e.

g., orange fur). The inactivation is random, resulting in an orange/black mosaicism. Quimera's different colored eyes can be explained by the white spotting gene that affects her eyes differently. One has a sort of normal color, and the other is blue, which is basically a lack of pigment. Despite her unusual appearance, Quimera is a normal feline who loves to snuggle up with her human, hide under bed sheets, and paw around the computer.