Beyond the back wall of the chamber, in a location that would once have been within the mound, is a replica of the 'Pattern Stone'. This was found buried under the mound, and has been put standing up in what is thought to have been its original location at a time when the site was a henge rather than a tomb. The patterns take the form of sinuous serpentine shapes that wind around both sides of the stone. Inside the tomb another stone has a small spiral pattern chipped into it, although its authenticity has been questioned.