In contrast to the grey of their parents and the rest of the clan, newborn leaf monkeys are orange.
This high-vis evolutionary trick is believed to have developed to stop babies from being separated from their mothers, as well as to protect them from predators (which see orange as a sign of toxicity) and even to remind the rest of the troop that they should volunteer for babysitting duties. After about three months, the babies start to develop silvery-tinged fur from the top down. (There is a point when their heads are grey and their bodies are still bright orange.)
These animals, native to Borneo, Malaysia and Sumatra, are keen explorers, so their bright hue allows mum to keep watch as they swing through the trees.