Abundant, unfamiliar with and seemingly unafraid of humans, large numbers of the creatures emerged and foraged in all directions at night.

Making querulous squeaks, the rats entered the Challenger expedition's tents and shelters in 1886, ran over sleepers, and upset everything in the search and fight for food.

[6] Said to be related to Rattus xanthurus of Sulawesi and R. everetti of the Philippines, this species was grizzled brown above and lighter on the underside.

[7] The rat is named after Captain John Maclear (1838–1907) of the British survey-ship HMS Flying-Fish, who collected the specimen from Christmas Island in 1886.

Although scientists were mostly successful in using CRISPR technology to edit the DNA of the brown rat to match that of Maclear's, a few key genes were missing, which would mean that the resurrected Maclear's rats would not be genetically pure replicas and would lack critical components such as scent and immunities.