FIG. 1 is a perspective view of a cube shelf showing our new design;

FIG. 2 is a front elevational view thereof; and

FIG. 3 is a right side view thereof, the opposite side being a mirror image of the side shown.

FIG. 4 is a perspective view of a second embodiment of the cube shelf of FIG. 1;

FIG. 5 is a front elevational view thereof; and,

FIG. 6 is right side view thereof; the opposite side being a mirror image of the side shown.

The broken line showing the inside of the cube shelf is included for the purpose of illustrating environment and forms no part of the claimed design.