Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5936909.

Balls for the purifier, or ponds in which symbiotic bacteria settle, that purify the water.

This is a quick 3d model remixed. I still haven't printed this. I made this to be self assembly and trying to avoid the usage of glue.

The more pieces you place in the filtration or tank, the better.