Dozens of you have sent me this video since yesterday. So what the hell IS this bizarre animal?
Well, it's definitely real. The exact species identification is difficult, but this seems to be a type of ribbon worm. The best guess at a specific species so far has come from Reddit user Exxocet, who suggests we're looking at a species called Gorgonorhynchus. He quotes J.F.G. Wheeler's study "The Discovery of the Nemertean Gorgonorhynchus and Its Bearing on Evolutionary Theory", which says:
The proboscis of the nemerteans usually consists of an introverted tube in a proboscis sheath, and it is everted like a finger of a glove that has been pulled "outside in'.
This new nemertean has also a proboscis which is retractile within a proboscis sheath, but the proboscis is branched. The branching is of the dichotomous type. During eversion, which takes place almost explosively, the short main trunk. first appears, then this dividess and the finer and filter branches appear, but since each one of these is the result of an evagination the effect is almost indescribable. It is as if a large number of lively, wriggling, minunte worms had been shot out.
So the strange white thing that seems to "erupt" from the worm is its proboscis. This is a tubular sucking organ that some worms use to feed. The worm is feeling out what it's sitting on, trying to find out if it can eat the hand.