I don't recognize it but from what I see of the board it is an EEPROM of so me sort or similar. If it has custom data in it of course the manufacturer can do you no good.
If you got the gizmos and software you can access the data in it, but if it is in question that data could be corrupt.
I do not believe it to be a MOSFET. It looks like pins 5-8 are all grounded and they use the ones on the other side, like many eight pin EEPROMs. If i t is a MOSFET I can see the four pins to the ground plane for heat sinking, but the other four, why four ? You got gate, source and drain. All four of those pins have feedthroughs on them.
Bottom line is I do not believe this to be a MOSFET, I believe it is an EEP ROM. If you have reason to believe I am wrong I am listening.