The robot jellyfish shredders
2 June 2015 Last updated at 00:14 BST
It has been estimated that jellyfish cause around $230m (£151m) of damage to South Korea's fishing industry a year and a further $70m (£46m) to power companies by blocking their inlet pipes.
The South Korean government is now funding a project to control numbers using jellyfish-hunting robots. When they find the jellyfish - they shred them.
BBC Click's Spencer Kelly went to the Korea Advanced Institute of Science and Technology (KAIST) - the MIT of South Korea - to find out more about the project.