A highly significant archaeological find including Moa bones and a Maori adze head has been discovered on an historic building site on Auckland's North Shore.

The bones and adze head were uncovered at Torpedo Bay, Devonport, where a new navy museum is being developed and due to open in August.

On a scale of one to 10 the find rated as a 10 for its historic value, an archaeologist with Opus International Consultants Limited, the principal design consultants for the museum project Mica Plowman told NZPA.

The find was thought to be more than 500 years old, possibly dating back to the 1400s.

The adze head and bones of the large, flightless and now extinct moa were found in a large fire pit.

The bones were part of a bird which was killed, cooked and eaten by Maori, Ms Plowman said.

The find was hugely significant because "first-settlement sites" were very rare and few had been excavated in Auckland.

Where the bones were found in the cooking pit indicated they had been discarded, indicating those who had eaten the bird had not been worried about running out of moa bones, highly useful for carving and working into items for everyday life.

Moa were believed to have become extinct in New Zealand about 500 years ago. They grew to about four metres tall and were heavily hunted by Maori, leading to their eventual extinction.

The site was found during work to renovate old defence buildings in Torpedo Bay, an historic part of Devonport and the site of a navy base since 1866.

Torpedo Bay was used in the late 1800s as a submarine mining station to defend Auckland against a possible invasion from the Imperial Russian Fleet. The mines spanned the harbour entrance and could be detonated from the shore if an enemy ship came up the harbour to attack.

It was also the base for the spar torpedo boats which were fitted with a long spar with an attached warhead and used to ram enemy ships. The boats were never used in conflict in New Zealand. They were highly unstable and considered to be more dangerous for the crew than for enemy ships.

Ms Plowman said the historic site was about 50 metre back from the harbour but when Maori used it, the site would have been on the water's edge.

It was a rare, exciting and very significant find, she said.

Early settlement sites were rare because they were often beach front sites which did not survive.

"Moa bones were a very valuable commodity in early Maori society. It was a robust large bone which enabled them to make large fish hooks and things out of it."

Historians say Torpedo Bay had many layers of history from the early days of Maori settlement in Auckland.

Kupe, the great Maori navigator, was thought to have landed his canoe in the bay about 900AD and named it Te Hau Kapua (cloud bank carried along by the wind).

Later one of the great `seven canoe' fleet commanded by Chief Hoturoa landed the Tainui people who were thought to have named a spring in the area `Takapuna', which later came to refer to the surrounding area.

In 1917, during World War 1, German Captain Felix Graf von Luckner was held prisoner at Torpedo Bay before being transferred to the island prison at Motuihe in the Hauraki Gulf.

The cell in the cliff where von Luckner was held still existed and would be part of the new navy museum's outside exhibits.