Thank you both for the information.  I am a novice and may not need to use it for a while, but would like to have access to a blade.  Again, thank you.

That is a hollow plane, great for creating custom molding or rounding corners.  Many in the craft will accumulate a collection of these in various sizes and their companion round planes to have lots of options for making obscure profiles.  Hopefully you also found the blade and can sharpen it up and put it to use!