This query is from Charlie who has been visiting from the USA...
"I saw an intertidal organism on Wharariki Beach (north end of South Island) that has me stumped. The first photo shows four of them, nice spiral coils, varying a little in size and color, tucked in among mussels, barnacles, and other familiar things. The second shot is the same scene, but with a 72mm lens cap for size reference. So I'd estimate the largest of my four spiral friends (upper right) is about 50mm in diameter.
Its hard to say for sure, but it appears the rest of the intertidal community is undisturbed in the gaps between the layers of spiral.
What are these fascinating organisms?
Hi Charley - great photos! The mystery animal is actually the egg case of the large siphon limpet, Siphonaria obliquata . It reaches lengths of 50 mm and although the adult is not obvious in your photos we may be seeing part of the shell on the far right of the photo with the lens cap. It is found around the South Island and southern North Island in the high and mid tide zone and hangs out in shady spots so may not be found next to its eggs. It is unusual as it has a primitive lung to aid survival when out of the water.
What a surprising and fascinating answer. Thank you! Do you have any idea how many eggs one spiral contains?
No sure, but many many thousands....the embryos are vary small and after a couple of weeks hatch into a planktonic larval stage and the egg ribbon disappears.
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