Sterna dougallii eggs. Very stealthy, those roseates.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/31852224@N00">Michelle Kinsey Bruns</a>
CC BY 2.0
<a href="//commons.wikimedia.org/wiki/Flickr" class="mw-redirect" title="Flickr">Flickr</a>: <a rel="nofollow" class="external text" href="https://www.flickr.com/photos/31852224@N00/3593068831">Roseate Tern Eggs</a>