The ornamental design for a spinnablerattleback, as shown and described.
FIG. 1 is a top perspective view of a spinnable rattleback showing my new design.
FIG. 2 is a bottom perspective view thereof.
FIG. 3 is a top plan view thereof.
FIG. 4 is a bottom plan view thereof.
FIG. 5 is a front elevation view thereof.
FIG. 6 is a rear elevation view thereof.
FIG. 7 is a right side elevation view thereof.
FIG. 8 is a left side elevation view thereof.
FIG. 9 is a top perspective view of another embodiment of my design, wherein the position of the indentions within the top surface is mirrored relative the first embodiment; and,