old 'refrigerator dish'??

Totally guessing at this one as maybe an actual kinda oldish "refrigerator dish" now missing its lid, just because it seems like that's what it should be...?? It is 8-3/4" long, about 5" wide, and 2-3/4" deep with a ribbed pattern to its exterior and a 'pebbled' pattern to its underside which also has a distinct oval shape impressed to its center. No other makers marks/info visible that I've found. Suggestions MORE THAN welcomed if anybody does have a real clue about it!! :-) :-) :-)