Watermelon Rock is a semi-circular piece of concrete in the Martin Luther King, Jr. Shoreline that has been painted as a piece of watermelon. At points in the past it has also been painted as an orange slice.
Someone re-paints the rock occasionally. Apparently not everyone likes it; someone complained to the supervisor of the MLK shoreline. When the supervisor declined to remove it, someone painted the rock black. Within days it had been re-painted as an orange slice. 1 According to the Alameda Patch, it was first painted on May 4, 1983 by Sandra Gibson and her friend. They had always thought it looked like an orange slice. 2