Sea Date, Lithophaga lithophaga, grows and lives inside the rocks, so it is practically impossible to see and film it unless the rock where it is found is shattered, an obviously illegal practice, prohibited by the regulations of all Mediterranean countries. Consequently, fishing is also prohibited and those who practice it are finally punished with severe and heavy sanctions, unless it is our usual friend the common octopus, Octopus vulgaris, who does it.

The answer of course is yes. As you can see from the movie shot in Sardinia this Castagnola Nera Chromis Chromis swims in an upside-down hole ...