Heat a large skillet over medium heat, add the oil and cook the onion for about 3 minutes. Stir in the garlic, the taco seasoning, cayenne pepper, and red pepper flakes. Cook for about 1 minute and then add the chopped shrimp. If raw, let it cook for about 2-3 minutes or just until turn pink. If pre-cooked, warm up the shrimp for 30-60 seconds. Stir in 1 tbsp of lime juice. Set aside.
Using a hand mixer, mix cream cheese and the remaining 2 tbsp of lime juice in a large bowl. Stir in the shrimp mixture and 2 tbsp of pecans, mixing with a spoon until homogeneous. Place the soft mixture over a large sheet of plastic wrap and wrap tightly forming into a cheese ball. You may need to cover the ball with another sheet of plastic wrap.
Store seafood cheese ball in the fridge until firm, about 2 hours. About 10 minutes before serving, mix the parsley with the remaining pecans in a large plate. Roll the cheese ball in the parsley mixture until covered and serve.