Separate crescent rolls into triangles and place about 4 slices pepperoni onto each one.
Top with string cheese piece, and then roll up as you would for a regular crescent roll.
Tuck both sides in to seal roll and pinch all seams tightly.
Roll crescent roll back and forth on counter top to further seal roll.
Bake according to crescent roll package directions.
Serve warm with warmed marinara sauce, if desired.