What is the ruling on zakat for what is extracted from the sea, and what is its nisab and its amount?

There is no zakat on what is extracted from the sea, such as pearls, coral, amber, and the like, similar to what is extracted from land mines, unless it is sold and reaches the nisab and a full year passes over it. Some scholars are of the opinion that zakat is obligatory on it because it is extracted from a mine. Others hold that there is no zakat on it due to the absence of a prophetic tradition or a consensus among the Companions mandating zakat on it, and because it is something the sea casts forth effortlessly. As for fish, there is no zakat on it, by the consensus of the scholars.