Panchajanya is the holy conch of Lord Krishna and the divine conch is also worshipped in Hinduism. One of the popular images of Lord Krishna in Hindu religions is that of Him blowing the Shankh Panchajanya at the beginning the 18-day Kurukshetra battle in the Mahabharata. There is an interesting story which explains how Sri Krishna came into possession of the Panchajanya.
The Guru of Sri Krishna was Saint Sandipani. After the completion of his education, Lord Krishna wanted to offer a Guru Dakshina. As Guru Dakshina Guru Sandipani asked Lord Krishna to find his lost son.
After searching for a while, Lord Krishna found out that the Guru’s son was captured and abducted by a demon named Panchajana. The demon lived under the sea in the form a conch shell.
The conch, Panchajanya, is named after this demon.
Another legend suggests that the Panchajanya was one of the items that appeared during the churning of ocean or the Samdura Manthan. You can read about it in this earlier article – Conch Panchajanya.