They seemed to be dots. Weeds grow faster, taller, and stronger than rice. While Hisaharu was thinking about the labor that paddies involved, he forgot the pain in his legs and feet.
Photo from:
http://www.city.komagane.nagano.jp/index.php?f=hp&ci=13076&i=13895
This photo is from the middle of Main Island. All rice fields are like this in planting season.