I would call them "rice krispie" pearls, which look like the breakfast cereal of the same name. Four of them-- the colored ones-- are dyed.
Rice krispie pearls were tissue nucleated pearls formed in the cockscomb mussel, Cristaria plicata. These pearls were common in the 1970s - early 1980s.
FW keshi, or second harvest pearls, come from the triangle sail mussel, Hyriopsis cumingii. The first harvest are tissue nucleated pearls such as the common potato pearls of the 1980s-early 2000s. After those are harvested, if the mussel is returned to the water, a new pearl will form inside the exisiting pearl sac. That will be a FW keshi. They are inexpensive because so many can be be harvested at the same time just from one mussel.