original: The color has been speculated to be due to organic compounds on its surface.
simplifications: The color might be due to organic compounds on its surface. The color might be due to organics on its surface. Some believe the color comes from organic compounds on the surface. The color may be due to organic compounds on its surface. The color is thought to be from organic compounds on its surface. It has been speculated that the is due to organic compounds on its surface. The color has been thought to be a result of the organic compounds on its surface. It is a belief that the color is caused by organic compounds on its surface. The color was speculated to be due to organic compounds on its surface. The color is thought to be that way because of the organic mix on its surface.