Black snails at tidal canal.

[AngieNg]

Hi folks,
found these un-IDed image of these black thick-shelled snails feeding in canal at the west coast park last year.
the shells were hard, smooth and really black, with equally black flesh.
Please can someone ID them? Thanks
Angie

[AngieNg]

Hi folks,
These black snails have been ID by experts at RMBR as "Faunus ater", found only in Singapore's west coast, but are widely distributed in the western Indo-Pacific region. Now they can be labelled!
Are they edible??
Cheers!