What Is This Bizarre Slimy Green Creature?

Plants and Animals





Photo credit:

Why is it pulsing? / Wei Cheng Jian

What is this creature in the video below and why is its every move terrifying?

 

[youtube https://www.youtube.com/watch?v=GQcer...]

 

Wonder no more: the green gloop is a ribbon worm (Nemertea) and the pink projection that curves over its body is its proboscis tongue.