The actinopods with glassy shells

Explanation

Radiolarians are a class of protists within the broader group of actinopods. They are known for their beautiful and intricate silica-based, glassy shells. These shells often have radial symmetry and are used for protection and buoyancy. In contrast, Stentor and Euglena are protists that do not have glassy shells. Stentor are ciliate protists known for their trumpet-like shape, and Euglena are flagellated and primarily photosynthetic, lacking any form of silica-based shell.