No idea on the seashell:(

[wolfi]

Hi Alumette,
it's family Ellobiidae, genus Pythia. As far as I know, three species are known from Bali and the surrouding islands: Pythia imperforata, Pythia pantherina and Pythia undata. Should be one of these species. For closer determination it's necessary to judge the lamellae and dentes in the aperture. A little bit difficult here because of the grains of sand...... :-\
Kind regards: wolf