Ten models of the different shapes of stones
Each models has something between 1000-3000 triangles
PBR Metal Rough Redshift Unity Standart Specular Unreal Engine 4 V-Ray included.
https://www.cgtrader.com/3d-model-collections/pbr-stones-set-01
https://www.cgtrader.com/3d-models/exterior/landscape/stone-11-set-01-pbr
https://www.cgtrader.com/3d-models/exterior/landscape/stone-09-set-01-pbr
https://www.cgtrader.com/3d-models/exterior/landscape/stone-08-set-01-pbr
https://www.cgtrader.com/3d-models/exterior/landscape/stone-07-set-01-pbr
https://www.cgtrader.com/3d-models/exterior/landscape/stone-06-set-01-pbr
https://www.cgtrader.com/3d-models/exterior/landscape/stone-05-set-01-pbr
https://www.cgtrader.com/3d-models/exterior/landscape/stone-04-set-01-pbr
https://www.cgtrader.com/3d-models/exterior/landscape/stone-03-set-01-pbr
https://www.cgtrader.com/3d-models/exterior/landscape/stone-01-set-01-pbr
https://www.cgtrader.com/3d-models/architectural/other/stone-02-set-01-pbr