Researchers have discovered live specimens of an extremely rare ant living in Singapore's forested Mandai area.

The ants were first seen in 2003, when entomologist Fernando Fernández named it after Tyrannosaurus rex -- its stubby, tiny mandibles had reminded him of the T. rex's tiny arms.

No live specimens of the ants have ever been found -- though ants of the same genus have been seen in India, Sri Lanka and Borneo, according to a new study.

So it was a bit of a surprise when entomologists Mark Wong and Gordon Yong found a colony of Tyrannomyrmex rex ants through direct hand sampling of the forest floor.

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What's more, the ants were found on land where rambutan, banana and durian orchards used to be. The forest was also regularly used as a training ground for the island's military and was littered with bottles and wrappers, according to Wong, a National Geographic Young Explorer, and Yong, who works at the National University of Singapore (NUS).

But it's a bit of a surprise that these T-rex ants survived at all.

In a study published in the journal Asian Myrmecology, Wong and Yong described the timidity of the ants when they were brought to captivity: The ants, when intimidated by an intruder, typically curled up and remained motionless until the intruder moved on.

The ants used their large stingers only once, when a millipede trampled all over multiple curled-up workers:

When researchers offered the ants common items found on the forest floor, they shunned most of them -- keeping their distance for both live and dead prey.

The ants wouldn't even get close to honey, Wong told National Geographic.

"I had a good laugh when I saw them respond in this manner to little millipedes, mites smaller ants, and basically whatever prey I tried to offer them," Wong said.

The researchers think that the ants probably eats tiny invertebrates or insect eggs.

"Considering their extremely timid nature, as well as their small, blunt mandibles... it is conceivable that T. rex are specialised predators of invertebrates which are much smaller than themselves, eggs of other invertebrates, or are scavengers," they wrote.

There are still many more questions to be answered -- for one, Tyrannomyrmexants lack organs that naturally secrete antiseptic compounds crucial for their hygiene, say researchers, even though they live in on the forest floor, which is full of bacteria.

A lone male that emerged from its pupae was also quickly cannibalised.

Though cannibalism seems a bit morbid, it isn't an uncommon phenomenon amongst ants. "[It's] has been documented in species from several (not all) ant genera for a long time," said Wendy Wang, a curator of insects with the Lee Kong Chian Natural History Museum.

Eating fellow ants has been one of several multiple hygiene strategies to "prevent the spread of pathogens on corpses," Wang, who was not involved in the study, said.

"Queens may sometimes also practise cannibalism as a method of gaining more nutrition and/or survival," she added.