FIG. 1 is a perspective view of the triangular curvilinear spa shell.
FIG. 2 is a top view of the triangular curvilinear spa shell.
FIG. 3 is a rear-view of the triangular curvilinear spa shell.
FIG. 4 is a front-view of the triangular curvilinear spa shell; and,
FIG. 5 is a side view of the triangular curvilinear spa shell.
The broken lines are for illustrative purposes only and form no part of the claimed design.