Thermostat too dirty

[ZafSC]

Hello. I removed the thermostat last fall during winterization, and now I wanted to install the new one, but the hole inside it look extremely dirty. Looks like grease and mud, not exactly sure. I didn't notice it previously, because it was full of water (or antifreeze) previously.
Attached are the pictures. Is there some method to clean it before I install the new thermostat? Or I just ignore it?
Thanks

 

[DeepCMark58A]

clean the surface and reinstall not abnormal

 

[cyclops222]

Might be normal in very polluted waters.

 

[Scott06]

Typical of any raw water cooling system used in fresh water. Knock off the big stuff and use it.

 

[cyclops222]

My 1976 evinrude is spotless in there.

 

[flashback]

My 1976 evinrude is spotless in there.

is it made of aluminum, probably. op is iron.

 

[Scott06]

My 1976 evinrude is spotless in there.

Great, your parents must be proud. On a cast block what the op shows is totally normal

 

[Scott Danforth]

use a wire brush to remove the rust flakes, install new thermostat, sleeve, and gasket and go boating.

extremely common on a raw water cooled boat in either fresh or brackish water.