An explosive device was discovered amongst shingle on the new Cowes breakwater.
The discovery was made at lunch-time yesterday by contractors carrying out reshaping work. Immediately they surrounded the item with sandbags, and raised the alarm.
Cowes lifeboat was launched at 2pm and was used to convey mobile coastguards from Bembridge to carry out an on the spot inspection of the device,.
It is thought to be an anti-aircraft shell from the Second World War. The lifeboat returned to station at 3.35pm.
It is expected the device will eventually be removed by Royal Navy personnel from Portsmouth.