"Why don't thousands of bats in a cave get confused? How do they differentiate their own location echoes from those of other bats?" This puzzling problem was sent in to curiouscases@bbc.co.uk by Tim Beard from Hamburg in Germany.
Since ecolocation was first discovered, this question has perplexed biologists. Hannah turns bat detective to try and track down these elusive creatures at The Queen Elizabeth Olympic Park in East London. This is where zoologist Kate Jones from University College London is using a network of smart sensors to find, identify and track wild bats.
John Ratcliffe from Toronto University chats bats and sonar with Adam to try and locate the answer. It's an unlikely tale involving gruesome early experiments, cunning electric fish and some surprising bat maths.
Send your Curious Cases for consideration to: curiouscases@bbc.co.uk
Presenters: Adam Rutherford, Hannah Fry Producer: Michelle Martin.