Ed Yong in Not Exactly Rocket Science:
Every year, in northern Myanmar, thousands of farmers pull tonnes of Cretaceous amber out of the ground, and send the glistening nuggets to local markets. For six years, Bo Wang from the Chinese Academy of Sciences and his colleagues have visited the markets and sifted through 300,000 of the glistening nuggets. It was a lot of work. Then again, it takes a lot of work to find animals that spent their whole lives trying not to be found.
Within the amber, Wang’s team identified dozens of ancient insects that camouflaged themselves by adorning their bodies with junk. They had short bristles and elaborate feathery tubes, onto which they stuck sand, soil, wood fibres, bits of ferns, and even body parts of other insects. They were the earliest animals that we know of to camouflage themselves, some 100 million years ago.
Many living creatures still embellish their bodies in debris. The aptly nameddecorator crabs, for example, look like walking bundles of algae and seaweed. The larvae of caddisflies live in tubes made of rock, sand, plants, and other underwater detritus, bound by silk. And one grisly species of assassin bug wears a coat made from the corpses of its ant prey.
More here.