It is 1825, nearing the peak of American whaling, and the seas are still crowded with whales. But hunting the mighty creatures means long, lonely stretches for whaling crews on voyages that could last for years.

It is a time before Sudoku, so sailors turn to scrimshaw – detailed etching on bone or ivory – to while away the hours. This skull of a rough-toothed dolphin, Steno bredanensis, becomes the canvass for images including potted plants, butterflies and flags. Sailing ships flank the back of the animal's head, while a checkerboard pattern marches along the mandible.

The origin of this piece is unknown, but it is thought to be the work of an American whaler working around 1825, judging by the flags depicted.

Cetaceans themselves can get creative, too. Some whales woo mates with love songs, and then cement their union with duetsSpeaker. Whales and dolphins could even be said to have their own cultures.

Whales can craft a story worthy of the most ambitious scrimshaw artist: their 25-centimetre long plugs of earwax can serve as detailed records of their life experiences.

(Image: AMNH/Elizabeth Nunan)

The scrimshaw skull is on display at an exhibition called Whales: Giants of the deep at the American Museum of Natural History in New York City.

Read more about whales and other ocean creatures in our mysteries of the deep sea topic guide.