What is a bottomless egg box?

On page 193 of The Complete Tightwad Gazette, in the section on trash-picking/Dumpster diving/treasuring hunting, Amy Dacyczyn writes out a list of all of her family's greatest finds. She mentions "an antique bottomless egg box (sold as-is for $5)." Google yields no results for bottomless egg box. What is this delightful-sounding contraption?