One of the examples of Flexi disc. https://news.nationalgeographic.com/2016/03/160305-songs-of-humpback-whale-record-challenger-deep-mariana-trench-microphone/

One of the examples of Flexi disc. https://news.nationalgeographic.com/2016/03/160305-songs-of-humpback-whale-record-challenger-deep-mariana-trench-microphone/ https://news.nationalgeographic.com/2016/03/160305-songs-of-...