Giant pearl

Ok my wife’s brother has asked to value and sell this apparent giant pearl from Philippines, can someone help me?

Does anyone have connections to buyers of giant pearls from Philippines?

No one wants to buy these items. People come here all the time with these giant clam growths and no one can sell them. They are not pearls. They have very little value, but might make a good door stop or a conversation piece.

A long time ago there was a giant clam growth that was promoted as being very valuable and the word got around that they could be worth good money. That is not true. The original "pearl" never sold.