Drain the shrimp and crab meat and gently mix together.
Add the Sea-horsey Seafood Horseradish mix and stir to combine.
Add the mayonnaise, celery, lemon juice, red onion, and capers. Stir to combine.
Let the salad chill in the fridge for 30 minutes.
Spoon salad onto crostini.
Serve on a platter.