Difflugia spec.
Difflugia acuminata, each shell c. 290 µm, The Netherlands

 

Two shells joined together. Probably the shell to the right has used the other shell as building material.

 

Difflugia rubescens with double pseudostome

 

Difflugia test with double pseudostome (P) - Photomicrograph Martin Kreutz
The same test as above - Photomicrograph Martin Kreutz