A flying structure, by the artist José María Yturralde, with title "Octaedro", 1976.
In fact, the structure recalls that of an octahedron.
You can see another photo of the same structure; or another flying structure by the same author.
© José María Yturralde
foto di José María Yturralde
The image belongs to the sections...:
Octahedron (3D geometry)
Polyhedra around the world (3D geometry)
Sculptures (Anthology of images)