Complex sentence: The main idol is a black stone statue Carved from a single block of basalt stone, the Budhanilkantha statue is 5 meters in length and it lies in a reclining position inside a recessed pool of water that is 13 meters long.
Split into simpler sentences: The main idol is a black stone statue carved from a single block of basalt stone. The Budhanilkantha statue is 5 meters in length and lies in a reclining position inside a recessed pool of water that is 13 meters long.