The Well of the Mimir
Pure entry. I made the details on the tip of the horn (barely visible) with Inkscape, the rest is made with Blender using procedural textures.
In Norse Mythology, Mimir had a well which provided him with knowledge. He drank mead from the well using a horn.
Odin, thirsty for the knowledge held only by Mimir and his well, traded his eye for a chance to drink from the well. Odin returned to Aasgard very concerned, for he had learned about the end of the world.