（作者单位：中国社会科学院考古研究所）
While Gelidium seaweeds can be collected by gathering fragments washed ashore, mass production of agar requires steady, large quantities.10 Harvesters in New Zealand during WWII had to “walk beside a boat, waist to armpit deep in water and feel for the weed with their feet.” Handling large volumes of wet seaweed (which yields less than five percent agar) was challenging. Then as now, when Gelidium is harvested by scuba divers from rocky seabeds, collectors have to understand the life cycle of the algae, find the most likely locations for its growth, and prevent overharvesting to safeguard future yields.
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Both are valid. Both are interesting.