學名：Ancyloceratina（勾菊石亞目）
年代：白堊紀
發現地：摩洛哥
說明：
「咦！這個像迴紋針一樣的化石是什麼生物呀？」相信大家都會有相同的疑問。
雖然大多數常見的菊石呈現螺旋狀，規則地由內向外環繞。但有些菊石的外殼擁有特殊的形狀，像館藏的這座勾菊石化石，便是例外。牠們是時間長流演化下的產物，也是生命淬鍊的痕跡。
Most ammonites feature planispiral shells, spiralling outwards in a distinctive pattern. However, just like this Ancyloceras seen here, some of them have unique shapes.
較原始的勾菊石形狀接近完整的螺旋，只有在最末及外端開放，像螺旋下的一個勾。以這種形狀而言，螺旋的部分便是氣室，而勾，即是住室。但到了白堊紀晚期，牠們的形狀更為多變，甚至出現了完全筆直的桿菊石、扭轉螺旋狀的塔菊石、奇形怪狀的日本菊石等等。雖說菊石形狀千奇百怪，但，什麼形狀都不奇怪，參觀完博物館的您，下次不要被對於菊石的既定印象給侷限囉！
Primitive ancyloceras had a shape approaching a complete spiral, with openings only found at the tail and exterior. The spiral portion are camerae used for floating, while the hook is where the organs of the ancyloceras resided. Later on, during the late Cretaceous, ammonites evolved into a great variety of shapes, such as the completely straight Baculites, the coiled Turrilites, and the misshapen Nipponites.