Shocked aquarium workers are celebrating after finding more than 150 baby jellyfish in a tank which has never been used to house the creatures.
The origins of the tiny animals remains a mystery but staff at the Sea Life Centre in Birmingham believe the newcomers may have arrived in a tanker of salt water brought to the landlocked site from the Dorset coast.
High levels of specialist expertise are normally required to breed jellyfish in captivity and their survival at the city centre attraction is being hailed as a "resounding success".
Aquarist Carey Duckhouse believes a Totally Tropical feature running at the centre probably aided their development.
She said: "The temperature of the water is warmer and this may have given the jellyfish a better chance of survival."
The biggest of the babies is the size of a fingernail and too small for staff to identify, but they are all believed to be a form of Cassiopeia andromeda or upside down jellyfish, normally found in tropical mangroves and lagoons.
They can grow up to 20 centimetres.