For a few hours on Sept 17, Dr John van Wyhe, a senior lecturer at the National University of Singapore (NUS), had a half-metre-long dead snake lying in a Ziploc bag in his fridge.

Discovering the "squiggly, grey thing" lying in the middle of a mountain bike trail in Bukit Timah the day before would turn out to be a "once-in-a-lifetime experience", Dr van Wyhe told The Straits Times.

"It was really bizarre, the weirdest thing I had ever seen," he said of his encounter with the already dead creature.

"It looked at first like it had no head and no eyes, with both ends resembling the underside of a thumb.

"Then I realised there was a tiny slit on one end which must have been its mouth, and saw scales, which made me realise it had to be a snake. What struck me was that it had no jaws."

Since then, the specimen has been moved to the Lee Kong Chian Natural History Museum, with experts identifying it as a lined blind snake - a reptile that had not been seen in Singapore for more than 172 years.

Before handing it over to the museum, Dr van Wyhe had transported his find back to his house in a Ziploc bag in his mountain bike helmet, carefully placing the snake in his fridge to keep it from being damaged further.

Also known by its scientific name Ramphotyphlops lineatus, the lined blind snake spends almost its entire life underground feeding on invertebrate prey. Nature watchers say its subterranean existence, as well as its worm-like appearance, has made it elusive to biologists and members of the public alike.

Dr van Wyhe has a theory about the snake's emergence in September, apart from his being in the right place at the right time.

"It could be due to the very unusual weather we had that month," he speculated.

"Because of the lack of rain and dry soil, the snake was probably starving in its natural habitat and was driven out to look for food."

The significant rediscovery has made waves among nature watchers around the world, with United States science and zoology writer Matt Bille pointing out that 172 years is the longest period he knows of a reptile going undetected.

In his blog post on Monday titled A Singapore Snake Sighting, Mr Bille wrote: "The discovery is an important reminder that a species may resurface after presumed extinction - even prolonged presumed extinction... So congratulations to Dr van Wyhe. Keep looking!"

On his part, however, Dr van Wyhe is sceptical that he will chance upon such an important sighting again.

"I will never see anything this unique again in my life," he lamented. "But we are rediscovering new species every year, so it will happen to someone else I am sure."

MOUNTAIN BIKING A GOOD AND BAD WAY TO SEE NATURE

A lecturer on Darwin and evolution at NUS, Dr van Wyhe, who came to Singapore from Britain in 2009, is also an avid mountain biker.

In addition to the sense of liberation he gets from travelling at speed over expansive terrains, he said, mountain biking is also an effective way of seeing Singapore's flora and fauna.

"The high speed means it is terrible as you miss 95 per cent of what is around you, but the vast distance you get to cover more than compensates," he said.

His discovery happened on one of his regular rides three to four times a week, the latest of many natural curiosities that he has seen up close.

At Pandan Reservoir, for instance, he once witnessed two 1.5m-long water monitors mating in the water for about 10 minutes.

"They were locked in each other's embrace and were rolling over and over."

In Kent Ridge, a wasp collided into a blue bumblebee just inches from his face. They fell by the trail and the wasp began stinging the bee vigorously, he recalled.

"I think there is a tendency to complain about there being nothing to see in Singapore when people haven't properly looked. To see some of the most incredible wildlife in the world right here is a great privilege."

Encounters with nature are important for conservation efforts, and an array of natural treasures await Singaporeans who are willing to spend more time in green areas, he added.

"I'm only an amateur enthusiast, which speaks volumes about what an ordinary member of the public can contribute to science. It's simply not true that nature here has been swallowed up by urbanisation."