https://en.wikipedia.org/wiki/Stone_spheres_of_Costa_Rica
"The spheres range in size from a few centimetres to over 2 metres (6.6 ft) in diameter, and weigh up to 15 tons.[4] Most are sculpted from gabbro,[4] the coarse-grained equivalent of basalt. There are a dozen or so made from shell-rich limestone, and another dozen made from a sandstone."
Basalt is paramagnetic and when in contact with the earth resonance makes biphotons in the weak uv range, which is good for people's mitochondria and makes plants grow better. This is like the Moai at easter island and I suspect the bluestones at Stonehenge.
I also suspect gabbro being a type of basalt does this too and these things were found buried in the soil where people were farming . Here we have limestone with inclusions piezoelectric calcite so that might explain the use of that. Sandstone possibly for silica? There is more stuff to work out but this idea might explain why they made them .
