Possibly Sci fi?

I saw a late night movie on TV, it would have been late 90s early 2000s. All I can remember is the main character (male in his mid 20s) finds a strange metal dome in a excavation pit. All his friends tell him it's just an old hubcap from a 1960s VW beetle, but he is convinced it's not because it has the wrong radius and it was impervious to extreme heat