Observation - Spirorbis spirorbis. Description: Here we have a few spiral worm cases on a dried seaweed frond.
Here we have a few spiral worm cases on a dried seaweed frond. I suspect few people report them as they are quite small - here between 2 and 5mm (yes, peedie)
The first picture shows case upon case with most of them coiled sinistrally (from the mouth) - they are, almost certainly, Spirobis spirorbis.
But there are others, precious few, coiled the other way, that is dextrally.
I'd be very interested to see uploads of spiral worm cases which are sinistral - left handed and also other regional variations.
The second pictures show size, the rule is in half mm segments.
The third shows a variation in tube structure.
The last, bottom right, picture shows a spiral worm tube inside an old whelk shell. It definitely coils tuther way.