A massive jellyfish invasion clogged the cooling intake systems at France’s Gravelines Nuclear Power Station, forcing several reactors offline in a rare, non-nuclear shutdown.

One of the largest French nuclear power plants was temporarily shut down after a swarm of jellyfish entered the water intake systems used to cool the coastal reactors, on Monday its operator said.

Four reactors at France's Gravelines nuclear power plant were shut down late Sunday due to a swarm of jellyfish in the cooling systems, operator EDF said on Monday, likely due to rising water temperatures because of global warming.