Maybe there were multiple species around, but you can see another fruit pod in the bg of http://www.inaturalist.org/observations/911110, the shape of which seems to suggest N. lutea ("mature fruits mostly less than 1.25 times longer than wide")
Nelumbo lutea is a species of flowering plant in the monotypic family Nelumbonaceae. Common names include American lotus, yellow lotus, water-chinquapin, and volée. It is native to North America. The Linnaean binomial Nelumbo lutea (Willd.) is the currently recognized name for this species, which has been classified under the former names Nelumbium luteum and Nelumbo pentapetala, among others.