a weight on a length of thong
This is a weight, typically of stone or other dense material, with either a hole at one end or a narrowing where a thong is attached. A groove about the “equator” of a rock is another possibility. It is used for small prey (or getting the attention of larger prey).
Because it is the sole weight in use, a Perdida can be larger than a bola’s paired stones.
It can also be used as a training tool, readying someone for the use of the more sophisticated sling and bullets.
A Perdida is essentially a sling where, after launching the bullet, the sling is lost. This weapon’s name means “The Lost One” and is short for “Bola Perdida”, implying it is half of a pair of bola weights on two strands. It was probably a weapon on its own for some time, however, and was probably the natural precursor to the sling.
Items of this general shape are lumped under the general name of “plummets” as in “plumb bobs.”
It appears the use of the Perdida is so obscure that archaeologists often don’t recognize them when they find them. Then again, some artifacts are ambiguous; they might have been Perdidas or they might have had some other function. They could be pendants, weights for making straight vertical lines, drop spindles, fishing weights, pendulums for divination, and so on.
It is also likely that they were used several ways by their owner. “One tool, many uses,” is the paleo way.