Macaques and wild boars might be some of the more commonly sighted creatures in Singapore's nature reserves and other green spaces.
Invertebrates (creatures without a backbone), however, are much less visible.
Save for this rather humongous worm.
One Riann Goettl Seymour spotted an unusually huge worm on the pathway near the entrance at Lower Peirce Reservoir on Sep. 13, she told Mothership.
Here's a look at the nightmarish-looking critter.
She estimated it to be around one to 1.5m long.
Goettl said that she and friend had tried to move the worm to the grass verge at the side of the path to prevent it from being stepped or trampled on.
Goettl posted the photos and videos of the worm to Facebook page Nature Society Singapore, where numerous Facebook users were left puzzled at what exactly it is.
Many speculated that perhaps the worm was an earthworm or millipede.
One person suggested that the worm might be a Giant Gippsland earthworm, which can grow up to 1.5m. This species however, is endemic to Victoria, Australia, meaning that it can be found nowhere else in the world.
However, as seen from close-up photos above, the worm has short bristles on its side, a trait that earthworms lack.
One Rene Ong has identified the worm to be a Polychaete.
Polychaetes refer to a large group of over 10,000 species of worms which generally inhabit marine waters. They are also known as bristle worms.
They vary widely in appearance, and mainly use their bristles for movement.
Ong stated that this particular species identified is estuarine, which means it inhabits areas like river mouths with brackish waters.
One Facebook user though, also identified it to be a "watwat" worm.
"Watwat" is the colloquial name commonly used by anglers to refer to this species. These worms are typically used as fishing bait.
There is a possibility that the worm could have been bait discarded by anglers fishing at the reservoir.
Still though, a fairly bizarre finding.
Top photo from Riann Goettl Seymour / FB