The naga/conch shell represents the fame of the Buddha's teaching which spreads in all directions like the sound of the conch trumpet. It is a symbol which fearlessly proclaims the truth of the dharma.
A note about bone beads: Tibetan nomadic life is hard, and in the cold there is little to eat. Water buffalo is a main staple in Nepal and Tibet and when an animal is used for food nothing is wasted. These amazing bone beads are handmade by artisans who recycle and reuse everything in daily life and spiritual practice.
Mala measures approximately 26 inches around. Bone beads are about 10mm, naga spacers are about 12mm.