Undulate

Undulate describes a feature as having the shape of a wave, with crests and troughs. A valve may be undulate on the margins or on the face.

Undulate2
Image Credit: Sarah Spaulding, Elizabeth Ruck
Light micrographs of Cymatopleura. On the left, a frustule in girdle view shows the undulations characteristic of the genus. On the right, the undulations are visible in valve view.