A few years ago I bought a bunch of river rocks. They are fairly large ~ I don't know exactly how big, but I can hold about 5 or maybe 6 in the palm of my hand. These are the rocks you see in craft stores all of the time. They are different shades of brown & polished very smooth. Real rocks, not the decorative glass.
Anyhow, this may be a dumb question

but is it Ok to add them to the turtle tank? Has anyone ever heard of toxic materials being used on these rocks?
The container simply states, "River rocks, 5lbs."
*By the way, I know all of the cons for having rocks ~ but these are too big for my turtles to eat & I don't plan on covering the entire bottom of the tank. Just want to add a few

Thanks