caption: The image shows a small piece of oyster shell sitting on top of a table next to a ruler, with a scale and a paper with a QR code on it placed on the surface. The oyster is a light brown color and has a smooth, glossy texture. The ruler is a standard measuring tool with a black handle and a white ruler at the end. The paper has a black and white QR code printed on it, and the scale is used to measure the size of the oyster.