I was out bicycling this afternoon on an unusually warm day, April 26th, 2009.I was just leisurely cycling about the Plymouth and Kingston, Mass. backroads. It was a bright sunny afternoon, temps in the 70's, light mixed cloud cover, somewhat breezy and pleasant. As I was cycling down the shore road which leads to "Rocky Nook" area of Kingston and the south side of Duxbury Bay, I stopped at the side of the road about 1/2 mile from the bay to rest.I had a clear sky view from there of the Kingston/ Plymouth/Duxbury bay region.I noticed a distinctly black circular/spherical object in the sky at cloud cover altitude hovering and fading in and out within the partial cloud cover. I thought nothing of it at initial observation; perhaps a large weather balloon, peculiar aircraft, or any number of possibilities. I would estimate the cloud cover height at about 10,000 feet, but would have to check the actual weather records. What initially intrigued me about the circular object was it's remaining fixed in place/ hovering as the clouds moved in their normal progression. The object remained in place for at least 30 seconds, and then started darting about in zigzag and then horizontal and vertical attitudes a seemingly erratic pattern. It then hovered/stayed fixed in place for another 30 seconds or so. From that point in time, about 2-3 minutes had elapsed already, the oblect/black sphere proceeded in arcing/loop like courses. By this time about 4-5 minutes had passed while I stood transfixed gazing upward at the roadside. There were several people in their front yard at the opposite side of the road, and I imagine they were perplexed at my remaining still while staying focused skyward. I didn't want to break my focus by alerting them to what I was observing, because past experience has proven that these anomalies often dissapear in a moment. This object/sphere ceased it's looping maneuvers at that moment (5 minutes had elapsed) and stood still. The object then proceeded in a distinctly straight nortwesterly course until it escaped my view beyond the tree line.