Wild capuchin monkeys are very selective about the best way to crack a nut, according to scientists.
Researchers from the University of Georgia, US, filmed the wild monkeys selecting the correct anvil and hammer for the job.
The footage reveals the animals are "selective about the materials they use", say the researchers.
The research team reported their findings in the journal Animal Behaviour.
The monkeys use pits in logs as anvils to lodge the nuts in place, while they use large stones as hammers to bash through the shells.
The research was published in December, but the researchers have now released this footage, in which the monkey can be seen "weighing up" the most appropriately sized pit.