A rare bird was spotted in the reflecting pool on the National Mall this weekend.

The Lincoln Memorial’s Reflecting Pool was once a popular destination for ice-skaters, and in the mid-1960s a senior U.S. official proposed turning it into a rink for the winter months.

“Ask yourself: Do you need to be there?” says Mayor Muriel Bowser.

An aquatic mystery of Washington, D.C. solved.

It should be back to reflecting by the week of June 16.

The parasite grows in the snails that live at the bottom of the pool.

The Lincoln Memorial Reflecting Pool is empty, and National Park Service workers are diligently ridding it of algae before refilling it.

The algae won. The National Park Service has drained the Lincoln Memorial Reflecting Pool as part of a two-step process to address algae blooms.

You might see the algae in the Reflecting Pool as a problem, but the algae lobby sees it as a solution.

Despite a $34 million renovation, algae blooms have started appearing in the Lincoln Memorial’s Reflecting Pool.