The Tesseract, secured within a briefcase
The Tessereact is a cube shaped object that is said to have unlimited power.
History
Thor
After the credits, Dr.Erik Selvig is taken to a S.H.I.E.L.D . facility where he meets Nick Fury . Fury has a briefcase with the Tessersct inside, stating that it is "power", and asked Selvig if he wanted to study it. Selvig , promted by Loki , agrees.
Captain America: The First Avenger
To be added
Johann Schmidt with the Tesseract