The latter is based on ridged horns shaped shell and a drum pierced by eight circular windows which are inserted between sixteen niches grouped by two .
The latter its hemispherical cap is cut by 24 concave grooves radiating around the top .
The latter , which its hemispherical cap is cut by 24 concave grooves radiating around the top , is based on ridged horns shaped shell and a drum pierced by eight circular windows which are inserted between sixteen niches grouped by two .