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Pinhole is a common defect widely seen in many archeological stonewares from different kilns and periods. It is usually a sub‐millimeter pit on the glaze that was believed to be caused by the broken bubbles during the firing process. We investigated the pinholes on a porcelain sherd from Yaozhou kiln of the Song Dynasty (AD 960–1,127), surprisingly, every pinhole corresponds to a flower‐like cluster observed through the microscope. The flower‐like clusters are composed of radial mullite whiskers and ε‐Fe2O3 dendrites, and its growth mechanism were proposed after detailed microscopic and spectroscopic characterizations. The unique chemical composition around the pinholes became the breeding ground for the crystallization of flowers, whereas the crystallization process further facilitates the formation of the pinhole preventing the glaze from restoring smoothness. Our results enriched the knowledge on pinholes and revealed the interesting crystallization assisted formation mechanism, which not only related to bubble rupture but involves the crystallization dynamics as well.

Spin is an important component of figure skating, one of the most elegant events in the Winter Olympic Games. It is always presented as an example of the conservation of angular momentum in mechanics textbooks. However, the physics behind it in the actual operation is not that simple. Herein, we analyzed videos of an elite figure skater with open source video analysis. The moments of inertia of her body in six different layback positions were obtained. The average ice resistance during her spin was found to be about 26N and was put into consideration in the following calculation. Twenty-two different layback spins that score the same basic value were discussed. The initial angular momentum a skater needs when executing a spin is considered to be the largest contributor to its difficulty; the suggested easiest spin among the 22 was thus found by comparing their initial angular momentum. This paper presents a strategy that may help figure skaters achieve a high-scored layback spin efficiently, and the process itself will be an inspiring example of applying theory to practice for physics students.