Hi Sophie,

Land snails are not my forte, but I believe the shells in the last picture
(#17, 18, 19) are Achatina, not Amphidromus.  I think they are probably the
widespread Achatina fulica.  Also, I believe that shells #12, 13, and 16 are
juveniles of that same species.  The other shells pictured with them are
Amphidromus, but I'll leave it to the experts to say which species.  Shell
#5 appears to be an immature fresh water snail of the family Ampullariidae,
genus Pila or Pomacea, and shells #6 and 7 may also be members of that
group.  Good luck.

Paul M.