Pliny the Elder [1st century CE] (Natural History, Book 9, 68): Jellyfish roam about and change their place by night. These have the nature of a fleshy leaf, and they feed on flesh. The itch they cause has a biting power, just like that of the land nettle. Consequently this creature draws itself in as stiffly as possible and when a little fish swims in front of it spreads out its leaf and enfolding it devours it. In other cases it looks as if it were withering up, and allows itself to be tossed about by the waves like seaweed, and attacks any fish that touch it as they try to scrape away the itch by rubbing against a rock. The same creature by night hunts for scallops and sea-urchins. When it feels a hand approach it, it changes colour and draws itself together. When touched it sends out a burning sting, and if there is a moment's interval hides. It is reported to have mouths in its root and to evacuate its excretions by a narrow tube through its topmost parts. - [Rackham translation]