Cuttlefish show they're as smart as kids in 'marshmallow test' study The marine mollusks demonstrate they're able to delay gratification for the reward of a better snack. Listen - 01:52 At Australia's Great Barrier Reef in 2015, a broadclub cuttlefish hunts for a pretzel stick. Or was it a marshmallow? Reinhard Dirscherl/Getty Images Treats can be hard to resist, no matter what your age or species. But a new study reveals that cuttlefish -- yes, the marine mollusk -- can adapt to a well-known psychological test given to human children, and learn to defer gratification in order to snag a better snack.