A number of unusual sea shells recently spotted on the shores of Papamoa beach are rousing the attention of beach-goers.

Steve Casey spotted a number of shells all along the water front. He says they're an interesting sight.

'They seem to be a type of sea snail. It's a mystery to me why they should be washing up after the recent storm and king tides.

'As I would have thought seas snails would not be easily dislodged and I believe this species' habitat is five metres and deeper.”

Bay of Plenty Regional Council senior environmental scientist Stephen Park confirms the species as a tonna cerevisina.

'These can grow up to 230mm and they are regularly found in our region. These shells are most common in the coastal waters of the north of the North Island down to East Cape on this coast.”

He says they aren't typically found on beaches.

'They live in shallow waters of about 20m near to the shore, right out to around 250 m at the edge of the coastal shelf.

'Full grown specimens in good condition aren't commonly found on our beaches as they have a thin shell that can be broken in the surf.”

Stephen says recent storms are one reason the shells may be seen currently on the shorelines.

'They are often pulled up in trawl nets and on occasion get washed up on Bay of Plenty beaches, particularly here in Tauranga, after swells or storms.”