Storage?

[Safewiz]

After pulling the rear seat from my 29, I found what looks like a storage place. Could someone tell me what it was originally used for. I know I should know this, but I don't. This is my daily and it would be a nice place to store some tools and small parts, and maybe even a small jack. I have been driving this car daily since Dec, 2015, about 150 miles a week. Just got around to pulling the rear seat because I thought my screw driver had fallen back there.