Are there any Object Databases for Ruby?

I cannot seem to find any Object Databases for Ruby (do not confuse with Document Oriented, 开发者_StackOverflow社区like Coach and Mongo).

Do more or less mature OODBMSs for Ruby exist?

Thanks.

I don't know much about it, but I believe that the MagLev implementation of Ruby will include an object database.

There aren't any mature ones — because it isn't typically done or desired by Rubyists.