硬い外骨格と短い脚を持つ甲殻類で、海辺や干潟の岩陰や砂の中で見つかる。体を丸めて外部の衝撃を防ぎ、主に海藻類や腐敗した有機物を食べる。波と日差しを避けて素早く移動し、海辺の清掃員として生態系を支えている。
A crustacean with a hard exoskeleton and short legs, it is discovered between rocks and sand on the beach or tidal flats. It can curl its body into a ball to avoid external shocks and mainly eats seaweed or decaying organic matter. It moves quickly to avoid waves and sunlight and serves as a cleaner in the beach ecosystem.