Unidentified, funny, little rocks

Spear throwers or "atlatls" are sticks used to extend the length of the thrower's arm, perhaps even adding some "whip" to the throw. These were in use well into the more recent times, even after the bow and arrow became popular (around 0 AD around here). For example I think they found a spear thrower on the body of a hunter whose remains melted out of the glacier in British Columbia and these were dated to something like 1100 AD. Anyway, here is an example of a spear thrower from the website Tangible Sanctity:This has two features of interest: a handle, and a hook at the back to hold the butt of the spear. Missing is any example of a counterweight - something added on the shaft to make the whole shaft heavier, or to change its recoil/follow-through characteristics.

For years, I have been bringing back curios from my surface collecting and imagining them to somehow be involved with spear throwers. Here is one of the nicest:It is slightly polished and - to me - clearly an artifact. There was a book (can't find it on my shelf at the moment) that called these things "bow tie" spear-thrower counterweights.

I found lots of other much less clear examples of similar rocks. Like this one made of slate, and obviously ground smooth in some places, flaked a bit in others.[A back story on this is that I did not collect it when I first saw it, then got to thinking and went back. It took most of the summer before I spotted it again.]

Here is something from the Google, a bit along these lines:So let's stipulate that there was some kind of a spear-thrower counter weight. Formally a "banner stone" that had a hole through it and, informally, a whale-tail or bow-tie shaped item that was bound to the spear-thrower. For better or worse, here are the objects I kept. You can say whether they even look like artifacts; let alone fitting my theory of spear-thrower counterweights.
But then there is a class of small rocks that I think of as "sharks" and which I bring home out of puzzlement rather than any understanding. Maybe these played the role of the "hook" at the distal end of the spear-thrower:I am convinced these are artifacts. Voice your objections in comments.

Meanwhile, here is in modern version of the spear-thrower hook from the Google:All the discussion of bird stones reminded me of the topic of spear-throwers and the question of the function of bird stones - their uniformity as well as the holes drilled through them, make it clear that they had a specific function.

Update: Here is some interesting stuff about the B.C. Iceman (from here)

Scientists believe Kwaday Dan Ts'inchi was a hunter, who lived roughly 300 years ago — but possibly longer. He appeared to be in good health when he died an accidental death on the glacier.

Among the findings, researchers have determined:

• He was in his late teens or early 20s when he died.
• He wore a robe, likely made from about 95 gopher or squirrel skins, stitched together with sinew.
• He carried a walking stick, an iron-blade knife and a spearthrower.