Adamantite upgraded symbol question

[Gaymit]

Ok so my question had to do with the gold circle symbol after you upgraded Lost Trove with an adamantite ore. I am curious of what it means and what it does. Any help will be appreciated. Thank you.

 

[Chaser]

The gold circle means that any upright medal placed there gets a higher boost. When you upgrade further you'll unlock purple circles which boost reverse medals further.

So for example an upright speed medal would gain a x2.00 boost in that slot whereas a reverse speed medal would only get a x1.10 boost.