That's a fanlike shell.

那是扇状的贝壳。

youdao

The final design uses a fanlike shape to form a spacesurrounding the cedar.

最终的设计采用了扇形平面，形成环绕着雪松的形态。

youdao

The scientists say the theory may explain a long-standing mystery: strange dark spots, fanlike structures, and spidery patterns that appear near Mars's southern pole every year.

科学家们说这个理论可以解释一个长久以来的谜团：奇怪的火星黑斑，扇状结构和每年出现在火星南极附件的蜘蛛状图案。

youdao

The camp was set up like a kraal, with thirty-odd trucks parked in tight groups to form a large, fanlike defensive circle.

NEWYORKER: The Taliban��s Opium War