This is rust, as your tray would have been stainless steel. Stainless steel is carbon steel with a nickel content, the higher the nickel content the better the stainless steel

Email us at stains@stonebenchtopcleaner.com.au and we can give you the solution to remove this without damage

Tileworks LLC Ps a poultice will not remove rust, it is for oil or oil based stains.

Note: that using anything caustic or high in pH, any cream cleanser etc will do damage just like in this video. Also do not use any acids as it will also damage the surface.

Rust is extremely hard to remove from any surface, but it appears you have engineered stone in pure white of some sort, Due to the gloss it is showing under lights.

Here is our Care & Cleaning Essential for Stone & Quartz