@drsukhendu-mukhopadhyay This is a lovely tooth from a shark of the genus Carcharhinus! As it seems to have been washed in from offshore and is a long-lived genus, it is hard to say how old the tooth is

This is called coquina, its crushed fossil shells compressed together. Because of it’s unique properties due to its composition, forts were built out of it which were said to “eat” cannonballs, as they simply sunk in rather than shattering the structures.

Very interesting thank you!