In 1999, the Philippine island of Luzon, home to the capital, Manila, and ~40 million people lost power for an entire night due to jellyfish. Roughly 50 dump trucks’ worth of jellyfish had been sucked into the cooling pipes of a coal-fired power plant, causing a cascading power failure. – WTF Fun Facts
Source: https://www.smithsonianmag.com/science-nature/jellyfish-the-next-king-of-the-sea-679915/