cycloids
... that cycloids are believed to have been driven to extinction when crabs spread across their territory?
... that <b id="mwFHI"><a href="./Cyclida" id="mwFHM" rel="mw:WikiLink" title="Cyclida">cycloids</a></b> are believed to have been driven to <a href="./Extinction" id="mwFHQ" rel="mw:WikiLink" title="Extinction">extinction</a> when <a href="./Crab" id="mwFHU" rel="mw:WikiLink" title="Crab">crabs</a> spread across their territory?