Identify snail

Nottnick

We have lots of these snails on our porch.

We have a sedum roof.

Can anyone help identify? They don't seem to be causing damage.

Thanks

Dovefromabove

Slippery Moss Snail?

http://www.naturespot.org.uk/species/slippery-snail 

BenDover

Brian? 

It looks like a slug form behind. Can't make out the shell.

Have a look here.

http://www.bnhs.co.uk/youngnats/wp-content/uploads/2014/05/Garden-snail-and-slug-sheet.pdf

Does look almost like it could be the first one on the list...