<i>Original description:</i> New Horizons cameras have spied swarms of mysterious "pits" across the informally named Sputnik Planum. Scientists believe the pits may form through a combination of sublimation and ice fracturing.
NASA
<a rel="nofollow" class="external free" href="http://photojournal.jpl.nasa.gov/catalog/PIA20151">http://photojournal.jpl.nasa.gov/catalog/PIA20151</a>