No idea on the seashell:(

[Alumette]

I think that the reason of the uncertainity of choice is in, as wolfi said,
in "rather similarity of several species" and in... the quality of my pictures (for what I`m so sorry). Yes, Diocris, I`ve already learnt the page on gastropod.com but alas....still no certain decision.
On this page <!-- m --><a class="postlink" href="http://www.conchology.be/?t=77&search=pythia&shells=on">http://www.conchology.be/?t=77&search=pythia&shells=on</a><!-- m --> - as well.
It may be P. scarabaeus as well as P.pantherina by apparence.
Il ne me reste que ... to take an "arbitrary decision' or ... obtenir a new camera If seriously... I have to read more oriented by your leads.
Thank you very much, my friends, for your qualified and experienced opinion!
PS. If be back on Nusa Dua I would bring a handful of such wonderful sand with me To be honest I have not found any information on the reason why the grains of sand are ball-shaped and where in the world there is a similar beach with such sand. It`s very interesting! Excuse-me for the flame :-[