[3] The holdfast of C. tomentosum is saucer-shaped and has closely woven strands giving it a uniform appearance.

[4] C. tomentosum is native to the north east Atlantic Ocean from the British Isles southwards to the Azores and Cape Verde.

tomentosoides, has been spreading to various parts of the world, and a study was undertaken in 2003 in Guernsey to see whether it was displacing or even eliminating C. tomentosum from the island.

[6] A similar study undertaken in 2000 on exposed shores in western Ireland showed that, as compared to thirty years earlier, C. fragile subsp.

When the fluids from the algae are ingested, the chloroplasts remain intact and photosynthetically active in the digestive diverticula of the slug for some days.