It is presented as a hut, a tower or a high rock and is sometimes likened to the Hotié de Viviane, a megalithic site in Brittany.

[2] Etymologically, an esplumoir would be "a cage where a songbird is locked away at the time of moulting: a dark and warm place where the bird sings in its own feathers".

In Méraugis de Portlesguez, the esplumöer merlin is described as being atop a high cliff having no doors, windows or stairs and is inhabited by twelve prophetic maidens.

[8] This place is mentioned by the poet Jacques Roubaud as being hot and dark, located at the top of "la roche grifaigne".

Jacques Roubaud also explains the shadow that Perceval sees pass several times above him, accompanied by the voice of Merlin, by supposing the metamorphosis of the magician into a bird.