Someone found a 9 mm bullet in a stairwell at West Babylon Junior High School on Tuesday.
Authorities ordered a staggered dismissal of the school Tuesday. No injuries or incidents were reported.
The school was closed Wednesday because of the snowstorm. A police officer was sent to the school Thursday as a precaution.
By Thursday afternoon, district officials had identified the student who brought the bullet to school.
"A junior high school student had apparently taken the bullet from a relative's house, found it of interest and decided to show some friends at school and further indicated that he was unaware that he accidentally dropped it. This was an extremely poor decision on the student's behalf, but please be assured that there was never any intent for malice or harm," Anthony Cacciola, Superintendent of West Babylon UFSD, said in a written statement.
The student was suspended pending the outcome of a hearing.