Millions of the rare pyrosomes – also called sea pickles or fire bodies – have mysteriously invaded the Pacific, stumping scientists. (Photo : Ami Ericson/YouTube)

The tiny pyrosomes – known as “sea pickles” or “fire bodies” – are incredibly rare, even in coastal areas. So scientists are puzzled over what’s going on in the United States’ Pacific coastline, which is getting overrun with millions of the sea creature.

According to a report from The Guardian, this mysterious little animal – only a few millimeters long each – is also called the “unicorn of the sea” for its rarity. Now, millions have washed up on the beaches of the West Coast, getting tangled up on fishermen’s nets and surprising local witnesses.

While the actual animal is miniscule, they do assemble in huge colonies. A report from National Geographic revealed that the jelly-like pyrosome is actually technically a…