This is an image of Tethys.
Click on image for full size
NASA/JPL
The Surface of Tethys
The surface of Tethys is heavily cratered, which means that the surface is very old and hasn't been changed. Tethys is more lightly cratered in one region, however. This may be a sign of some internal activity in the past. There are also several trenches across the surface. These are further indications of active processes in the past.
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