How old is the computer, SgtPepper?
If it is new, I'd be heading to an Apple dealer and asking that it be taken apart to have any more of the offending little blighters removed under warranty.
If it is older I'd be wondering whether a young child , perhaps, has had access to the computer and been "posting" the beads in through the drive slot or some such (such things have been reported here before, though not with silica beads).
Regardless , if the beads are definitely coming out of the computer they need to be cleaned out, especially if they are in something mechanical like the optical drive.
Cheers
Rod