Kylesa is a Sludge Metal / Psychedelic Rock band from Savannah, Georgia, and was founded in 2001. To this day they have released five studio albums with Spiral Shadow being the last one, released in 2010.
The cover for this brilliant release (one of my 2010 Top 10 albums) was done by the artist Santos and shows the endless spiral of a tree (being continued in the booklet) containing a special kind of symmetry: The helical symmetry. The most common examples of helical symmetries are drill bits or springs.
“It can be thought of as rotational symmetry along with translation along the axis of rotation, the screw axis. It can be visualized as the tracing in three-dimensional space that results from rotating an object at an even angular speed while simultaneously moving at another even speed along its axis of rotation.” (source)