śankh (shankh, vallamberi shankh, śankha, cankam, canku) trumpet made from a whole conch (Xancus pyrum) shell, highly polished with a simple six petal flower design scratched into the surface.
The sound of this conch symbolises the primordial and sacred sound 'Aum'. The conch is almost exclusively a ritual instrument although it may be used to represent divine intervention in performances of the Kathakali dance drama of Kerala.