Reminds me of some Bushcrafting/Aboriginal/Ancient way of cooking I was looking at before, the well known Ray Mears cooked some Venison in a similar way, I'll have to try and find the video of it on youtube somewhere, its well worth the watch, from what I remember he cooked it with rocks that had been heated from a very hot fire in a pit, wrapped it in either pine boughs or some other form of greenery, put it on the rocks, covered it with more rocks and then capped the hole with something...my memory of it fades off there!

I'd love to have a go at something like that, still building myself up to do some mussels on the beach when I go, but having any kind of fire on any beach in the UK is a difficult prospect...they seem to think the beach will set alight!