These rare organisms shown in the image below, jellyfish-like, as described caused California power plant to shut down as they dwell and cling on the structures of the power plant.
The consistency of the organisms are jellyfish-like but these are called scalp.
Tom Cuddy, the senior manager of external and nuclear communications for the plant’s operator, Pacific Gas & Electric, said that these organisms were discovered during a routine check on the power plant structures.
I wonder what kind of plants, if any they have fed on. Its interesting that something as small as a jelly fish can shut down a nuclear plant!