The pathogenesis of ectopic gastric mucosa is a matter of debate between a congenital-embryological-and an acquired origin-consecutive to a gastroesophageal reflux (GER) like Barrett's esophagus -, the most commonly accepted theory being that these areas are embryological remnants.
Standard size latex filled helium balloons stay afloat for approx 8 - 12 hours, metallic helium filled balloons float for 2-5 days. I have found that a 36 latex helium filled balloon can stay afloat for a number of days due to the thickness of the balloon and the massive quantity of helium.
Helium Balloon Chart-How many balloons will a tank of helium fill? Approximate Cylinder Height Approximate Cylinder Weight Cubic Feet of Gas Will Inflate No. 9 Balloons Will Inflate No. 11 Balloons Will Inflate No. 14 Balloons 56 110 lbs. 244 800 430 215 48 70 lbs. 110 350 210 105 25 25 lbs.