This kina was found on Fisherman's Bay on Tiritiri Matangi Island. It is a sea urchin shell - they are a shellfish endemic to NZ and are often called sea eggs. They are found in waters all around NZ and are regarded as a delicacy by some. When they are in the sea, they are covered by a very spiny outer layer.
@golftragic If you get to NZ next year, make sure you allow time for a visit to our place and time to go to this marvellous island - I am sure @julzmaioro and I will be keen to accompany you!
@dide Not sure whether or not we'lll get across the ditch next year, but should be there within the next two years. Unfortunately, the golf trip we thought we'd be on was fully booked, mostly by the people on the preceding trip. Long story, shan't bore you, but we're very unhappy about it.