The discovery was made by workers at the Cemex marine aggregates plant in Northam yesterday morning.
A team of Royal Navy bomb disposal experts rushed to the scene and took the 12-inch bomb shell away.
Workers had found it in sand and gravel that had been dredged off the Solent and was being processed at the site in Belvidere Road.
Police were called, but did not have to evacuate the site or set up a cordon.
A spokesman for Cemex said the discovery of such shells was a “run of the mill” occurrence and that staff are well-trained to deal with the finds. The bomb disposal experts removed the inert shell, with a Royal Navy spokesman saying it had not posed any danger to life.