Mimer, known as the wisest in Norse mythology, the head in the well.
The base is an opaque PR101 pompeii red with clear blue shimmer, what I imagine the water would have looked like.

These photos have been edited to best show the accurate colour but please keep in mind that colours are shown differently on different screens.
 
The full range of Julia's paints are available in half and full pans at Julia's Etsy store. If you live within the EU, please go to Etsy for the best shipping price and delivery times: https://www.etsy.com/uk/shop/JuliaKArtStudio