<i>Epidendrium billeeanum</i> (synonym : <i>Epitonium billeeanum</i>) Wentletrap snails with their egg masses on a <i>Tubastraea</i> cup coral.  These snails feed on the cup coral via a long feeding tube that they introduce into the cups to get at the polyps inside.
<a href="//commons.wikimedia.org/wiki/User:Nhobgood" title="User:Nhobgood">Nhobgood</a> Nick Hobgood
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>