The whole group of plants we lump under the taxonomic classification of citrus are really changeable. It's out of this changeability that we get new varieties. Some of these can be quite fanciful, almost dream like fruit which is where the origin of the name chimera comes from. Buddha's Hand is a pretty dream-like fruit.
These changes are a genetic mutation that occurs in a branch or twig, and if that tissue survives, it can produce new shoots (called sports or chimera) with characteristics different from the those of the mother tree. These mutations can affect the color of the rind or pulp or the shape of the fruit.
Leaves on these twigs can have a different shape or size have a variegated color.
Mutations can cause the development of multiple buds, creating bunchy growth or “witches' broom.”
A chimera can produce an improved crop: some of today's cultivars were propagated from chimeras, such as the variegated pink lemon.
Usually sports are of inferior quality and should be avoided as propagation material. Prune sports that obstruct normal growth or interfere with harvest.
But some of them are so weird you just want to keep them around. This one showed up on one and only one tree branch in a lemon orchard. It looks like citrus scab, sort of, but on only one branch of one tree.
Some of the changes that you see in a tree can also be symptoms of a whole lot of other problems, like nutrients, Huanglongbing or herbicide damage. Check out some of the symptoms:http://ipm.ucanr.edu/PMG/C107/m107bpfruitdis.html
Some chimeras are yet to be found out. This image of spiral tattooing showed up for several years ago in a Meyer lemon orchard. It was erratic and inconsistent in a tree, not typical of a chimera. The orchard was finally removed because it wasn't making money. Now it just seems like a dream and will never know if it was a true chimera.