Seeing an octopus stack coconut shell halves with its eight long arms was surprising enough for researcher Julian Finn. But the sight that came next was even more unexpected: the octopus sat inside the shells and scuttled off across the sea floor on its tentacles, carrying its makeshift shelter along with it.

"While I have observed and videoed octopuses hiding in shells many times, I never expected to find an octopus that stacks multiple coconut shells and jogs across the seafloor carrying them," Finn told LiveScience.

It's the first time that invertebrates have been observed acquiring tools for later use. The veined octopus was captured on video as it built and moved its new home.

A marine biologist at the Museum Victoria in Australia, Finn witnessed the feat along with the rest of his team while diving underwater off the coasts of Northern Sulawesi and Bali in Indonesia.

They were there to study another species, the mimic octopus, but wound up observing 20 veined octopuses as they collected, arranged, transported and wore their new ‘portable armor’.

Some of the octopuses were even seen pulling the discarded shell halves out of the sand and squirting jets of water at them to clean them off.

"I could tell that the octopus, busy manipulating coconut shells, was up to something, but I never expected it would pick up the stacked shells and run away," said Finn. "It was an extremely comical sight — I have never laughed so hard underwater."

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Makeshift shelter is first known instance of an invertebrate acquiring tools for later use.