People with a fascination for marine life would probably have heard of nemerteans, commonly known as ribbon worms.
Black and white ribbon worm (Baseodiscus delineatus), Terumbu Pempang Darat;
Red ribbon worm, Kusu Island;
(Photos by Ria)
Most ribbon worms live in marine environments, with a small proportion adapted to freshwater habitats. Just earlier today, I learnt that a small handful of nemertean species have actually managed to colonise the land, and that they can be found in Singapore!