Final answer:
The shell or Russian shell strop, used for sharpening straight razors, is made from leather. This strop provides a fine surface for maintaining the blade's sharpness.
Step-by-step explanation:
The shell or Russian shell strop is made from leather. This type of strop is traditionally used for sharpening straight razors. A strop can come in various materials, each giving a different honing experience to the blade's edge; however, a Russian shell strop is specifically recognized for its leather composition, which provides a fine abrasiveness perfect for maintaining the razor's sharpness.