䗴

* 古无脊椎动物，形状多样，最常见的呈纺锤形，壳小，大部分为石灰质，最早出现在石炭纪，到二迭纪末期灭绝，是划分这两个地层的标准化石之一

(translated) Ancient invertebrate animals, diverse in shape, typically spindle-shaped, with a small, mostly calcareous shell, first appearing in the Carboniferous Period and becoming extinct by the end of the Permian Period; they are one of the index fossils for stratigraphically dividing these two geological periods