The ornamental design for a storagebox, as shown and described.
FIG. 1 is a front top perspective view of the storage box of the present invention;
FIG. 2 is a bottom perspective view of the storage box shown in FIG. 1;
FIG. 3 is a front view of the storage box shown in FIG. 1;
FIG. 4 is a rear view of the storage box shown in FIG. 1;
FIG. 5 is a right side view of the storage box shown in FIG. 1;
FIG. 6 is a left side view of the storage box shown in FIG. 1;
FIG. 7 is a top view of the storage box shown in FIG. 1; and,
FIG. 8 is a bottom view of the storage box shown in FIG. 1.
The drawings illustrate a storage box as shown in the drawings. Stippling and/or contoured lines are included in FIGS. 1 through 8 to depict surface curvature, flatness, texture, or other shapes.