cleaning symbiosis
... that in 420 BC, Herodotus claimed Nile crocodiles had a cleaning symbiosis with a bird ?
... that in 420 BC, Herodotus claimed Nile crocodiles had a <b id="mwBuE"><a href="./Cleaning_symbiosis" id="mwBuI" rel="mw:WikiLink" title="Cleaning symbiosis">cleaning symbiosis</a></b> with a bird <i id="mwBuM">(pictured)</i>?