sentences:  Sheets of different metals remained in the seawater for four months and then were examined.Two harbour ships were also used in this test, one with an additional zinc band, the other with an iron one.Davy observed, that while the zinc and iron themselves became covered in carbonate that allowed weeds, plant life and insects to attach themselves to the metal, the copper sheets that were connected to cast iron or zinc parts were free of any attached life forms or discoloration.