They're like aliens from another planet. There are over 300 species and counting, from the size of your fingernail to 10 metres across. They live on the ocean's surface, and in its darkest depths. But how intelligent are they, really? How do they use tools? And what's it like to meet one in the wild? Eminent marine biologist and science communicator Helen Scales joins Hannah in the studio.

Also - meet Gretchen Früh-Green, one of the scientists who discovered the Lost City, which some believe could be the origin of all life on Earth.

Follow us on IG, X and TikTok for bonus content and to see footage of the world's biggest octopus nursery: @oceanspod.

Watch the coconut-carrying octopus here: https://www.youtube.com/watch?v=RUN6c5yWJhQ

If you want to know more about the oceans and how to protect them, come and join us here: https://act.gp/life-under-water.