Black rats, or Insects the size of lobsters?
I'd vote for the tree lobsters. Their story is quite endearing.
Six-Legged Giant Finds Secret Hideaway, Hides For 80 Years : Krulwich Wonders... : NPR
One day in 1918, a supply ship, the S.S. Makambo from Britain, ran aground at Lord Howe Island and had to be evacuated. One passenger drowned. The rest were put ashore. It took nine days to repair the Makambo, and during that time, some black rats managed to get from the ship to the island, where they instantly discovered a delicious new rat food: giant stick insects. Two years later, the rats were everywhere and the tree lobsters were gone.
Totally gone. After 1920, there wasn't a single sighting. By 1960, the Lord Howe stick insect, Dryococelus australis, was presumed extinct.
On Lord Howe Island, their former habitat, the great-great-great-grandkids of those original black rats are still out and about, presumably hungry and still a problem. Step one, therefore, would be to mount an intensive (and expensive) rat annihilation program. Residents would, no doubt, be happy to go rat-free, but not every Lord Howe islander wants to make the neighborhood safe for gigantic, hard-shell crawling insects. So the Melbourne Museum is mulling over a public relations campaign to make these insects more ... well, adorable, or noble, or whatever it takes.
They recently made a video, with strumming guitars, featuring a brand new baby emerging from its egg. The newborn is emerald green, squirmy and so long, it just keeps coming and coming from an impossibly small container. Will this soften the hearts of Lord Howe islanders? I dunno. It's so ... so ... big.
But, hey, why don't you look for yourself?