Here’s a little video featuring Thuricola, an organism which lives within a lorica. Its lorica has a nifty feature, a valve-like door that prevents intruders. Thuricola often lives in pairs and as with many lorica dwellers, it can retract within the safety of its home in a small fraction of a second.
I am prone to mistakes when it comes to identifications, so any corrections will be appreciated!
https://www.youtube.com/watch?v=TqDdytkM8io 