While little is known about the chart and its purpose, the iconography is incompatible with other carvings of the Anuradhapura period (3rd-10th Century AD). The chart"s centre is made up of seven concentric circles divided by parallel vertical and horizontal lines. Rectangular compartments contain small, crossed circles. To the untrained eye, there are figures resembling umbrellas or bow and arrows, a kite, wavy lines and cylindrical shapes. An outer ring depicts marine animals: fish, turtles, seahorses.