Remove shells and devein all shrimp.
Check all mussels. If any are open and don't close immediately after tapping, discard, it means the mussel is dead. Throw away any cracked shells. Rinse under cold running water.
Add water to a medium size pot (enough to cover seafood) and bring to a boil over medium heat. Add all seafood to pot and cook for about 5 minutes until shrimps are translucent and mussels open. Drain in a colander. Let cool for a few minutes and remove mussel meat from shells. Set aside.