Surface Tension
David Kirkby (<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/cdm/">Flickr user darkmatter</a> / <a href="https://en.wikipedia.org/wiki/User:Dk_matter" class="extiw" title="wikipedia:User:Dk matter">Dk matter</a> at <a href="https://en.wikipedia.org/wiki/" class="extiw" title="wikipedia:">English Wikipedia</a>)
CC BY 2.5
<span class="int-own-work" lang="en">Own work</span>, (<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/cdm/53197139/">Flickr photo page</a>)