A very unique multicolored fur pattern for domestic cats, it combines black fur with orange/yellow fur mixed very closely, creating a color pattern similar to a tortoise's shell.
The vast majority of tortoiseshell and calico cats are female due to the genetic basis of cat coloration. Males are infertile due to an intersex condition, typically being XXY.
Some torties have a 'split-face' pattern as depicted in post #6879810. This is sometimes incorrectly attributed to genetic chimerism.
See also
Calico cat (also known as tortoiseshell-and-white)
