Up to 30 families were evacuated from their homes and 170 children were moved to a community centre during the security alert in Crumlin today.
The device, found outside an unmanned police station, has been removed for examination and the families have been allowed to return home.
It is the third school to have been affected by security alerts in the Antrim area.
A pipe bomb was picked up by a pupil in the playground at St Comgall's Primary School on Monday. It was apparently left by loyalists.
