Those look like conch or whelk shell beads. They are ground. Most today come from SE Asia, where they are pretty much hand made, so they can be very difficult to tell from the originals. FWIW, if those are origional beads, that many, without some sort of documentation explaining how the first person got them, means that those beads have a really excellant chance of coming from a grave.
Those beads look in too good of shape to have been lying in the open or even buried, I suspect they are modern. Bill