Tangram is a map between objects and relational databases; persistence is not the main point, it seems to me. So I'd go with something like Object::Schema or Class::Schema, just to name one of Tangram's core ideas.

Don't feel bad about Tangram not being an evocative name. I scratched my head about Postgres, which is a pun on Ingres. What does a classical female portait painter have to do with databases? :)