Pearl is an important material for repairing the statue of Poseidon. Click on Poseidon Statue to gain Poseidon Shelter skill, which can not only reduce the probability of seagulls making trouble while fishing, but also reduce the probability of encountering sharks.
If you come across a bunch of pebbles surrounded by a wild flower while exploring, you will find a wild treasure. Just dig down at the location of wild flowers, and soon you will find a building similar to the previous dungeon, where random materials will appear in the treasure chest.