Thuricola is a freshwater Peritrich ciliate that lives inside a lorica, attached to substrate in its environment. Identical in appearance to the Peritrich Vaginicola, the only way to tell them apart is the presence of a one-way valve that Thuricola builds into its lorica to protect it from predators.

This video takes a close look at this one-way valve. It’s amazing to remember that this is a single-cell organism, with no nervous system or intelligence, but somehow it knows to build this one-way valve for protection.