Walking on cliff’s edge?

This tiny gastropod is one of the smallest shells that we can observe in our sea. I think it’s much easier to spot it if it chooses to go for a walk over the Mediterranean's biggest shell Pina nobilis! In this photo, given to us by our friend Sokratis Karalis, the small shell looks like walking between a cliff and a river (it’s a Greek expression don’t blame me if you didn’t understand). I am very happy when I find nice pictures from Mediterranean not so fancy animals. It is very hard to tell which of the Bittium sp. it is but most often we meet at the depths the Bittium latreillii (Payraudeau, 1826).
Sometimes I have detected Bittium sp. between urchin spines so I think these tiny animals are nature’s admirers like all of us.