Climate activists on Thursday morning dumped wheelbarrows full of manure at the White House, ahead of President Joe Biden’s climate summit with more than 40 world leaders.

The activists, affiliated with the group Extinction Rebellion, assured the Washington Examiner that the content of their wheelbarrows was actually manure, even though from afar it appeared to be tightly packed dirt. A smell test confirmed the claim. The activists dumped about 15 loads into a pile on top of which they planted a sign reading, “Stop the bulls—.”