NASA’s Mars rover Curiosity acquired this image at Ogunquit Beach, Bagnold Dune on March 29, 2017, Sol 1651. Red arrows point to spherical ooids. Green arrows point to eroded ooids with dark nuclei. The ooids range from 0.2 mm to 0.4 mm in diameter. See scale bar at https://www.flickr.com/photos/105796482@N04/33605046591/sizes/o