Rock pools were created when the tide went out and left collections of water behind. Turlough viewed them as a metaphor for the TARDIS crew: "a group of creatures stranded when the tide [went] out, and none of them happy to be stuck with each other".
Turlough and Nyssa looked at rock pools on the shore of Ambermouth. They found anemones, which Turlough proceeded to poke with a stick. The Fifth Doctor considered them to have a "certain fascination". Tegan Jovanka preferred the explanation that Turlough had "an affinity with things that lurked under boulders". (AUDIO: Eldrad Must Die!)