After walking back up from the souterrain John Easson showed me a cup marked stone and 5 querns.
The cup marked rock has 2 cups about 2" wide and deep plus 3 smaller cups on one side. On the other side there is one cup also "2 wide and deep. Sadly this stone/slab has been broken and maybe there is an another part lying somewhere.
Also in the collection were 5 querns in various conditions. Several querns can also be seen in Alyth museum.