DIATOMS: Actinoptychus heliopelta from a Smith, Beck and Beck Slide

c. 1862

This antique microscope slide, about 160 years old, contains the beautiful fossil marine diatom known as Actinoptychus heliopelta. Heliopelta has earned the nickname the Iron Cross Diatom. It illustrates that relatively large puncta of a diatom may not be the smaller areolae, which are only resolved with the 20x and higher magnifications:

This is a 3-D model created with Helicon Focus stacking software:

These videos illustrates the three dimensional stucture of the diatom: