Which design type is known as an "end" or "comer" design for a casket shell?

The design type known as an "end" or "comer" design for a casket shell is the elliptic shape. This shape features a rounded end, which is signature to its structure and gives it a distinct look compared to other casket designs. The elliptic casket provides a more graceful and flowing appearance, which can evoke a softer, more comforting aesthetic.

In contrast, rectangular caskets are characterized by straight lines and right angles, making them less aligned with the "end" or "comer" description. Similarly, round caskets, although they may have a curved form, do not typically embody the characteristics associated with an elliptic design. Pentagonal caskets, while unique in their shape, do not fit the traditional casket design rules applied to most funeral services.

Therefore, the elliptic design's curvature and shape are what make it the correct answer as an "end" or "comer" design.