Found this inside a oil cooler? Zinc Anode?

[The Kickass One]

It was loose and not attached. Edge marine jet boat. Zinc anode?

Anyone have an idea?

 

[NoBrakes!]

Yessir, one of the threaded plugs in the heat exchanger is usually an anode. That piece corroded off of its threaded end

 

[2kDoo]

Those stop leak pellets don't look the same as they used to haha jk.
Glad you got it figured out !