Those on the north side are alternately round and octagonal (similar to the arrangement in Canterbury Cathedral choir), while those on the south side are of a more complex shape and uniform design.
This early form of sundial was used by a priest to calculate the time of services (mass), by placing a or small rod into the central hole of the circular of semi-circular dial to cast a shadow.
A similar scheme of red and black paint was applied within nearby Chichester Cathedral around the 1240s.
An article on the medieval paint has been published in the Evidence of the Norman artists who worked within St Mary's has also been discovered, in the form of an oyster shell colour-dish, mortared into the inside face of the north aisle wall of the ruined nave.
On the first octagonal column on the north side is an ornate cross carved into the stone.
This is thought to commemorate a visit by the Patriarch of Jerusalem or some other important person at the time of the rebuilding of the chancel.