Now I tried to cut the original message and remove from the text the specific french "signs" ie accents, etc.
 
This is a minute answer to those asking for cone habitat info.
 
I read about conus regius being found under slabs. In Guadeloupe (central caribbean) they are 90% of times caught just resting on a barren rock, but most often with the front in a hole or crevice. The only one I found under a slab was a juvenile. Usual depth between 3 and 15 meters.
Conus spurius is caught by a sand-sucking dredge on coral sand+rubble at a depth of more then 20 meters (60 feet).
Conus daucus and conus magellanicus are caught on flat rocky bottom covered with small algae (english lawn type but 3mm high), from 1 to 10 m.
Daucus has also been caught on sand and small rocks.
Conus mus is caught on baterred (is that english? where the waves break) reefs between 0 and 2 m.
Conus mindanus is caught buried in sand from 10 to 20 meters; So is conus attenuatus.
Conus ermineus is caught in crevices on blocks of rocks, pretty deep.
Conus granulatus is said to be caught in crevices on battered rocks, but I know of 3 caught in sand by coral reefs in quiet areas???
Switching area,
Conus desidiosus is caught on Tenerife (Canarias) from pools above sea level to a few meters deep under slabs in rocky areas with algae. They live in colonies and can crawl upside down under a rock (I found several having  group sex), which is not true for many cones, as I noticed in my aquarium.
 
Other cones another night, it is too late.