Thin irregular branches. It was found in a dried out condition. Possible identification 'Spongonema tomentosum'.
No interactions present.
.. difficult - Spongonema usually grows on other seaweeds such as fucoids (was this apparent). It is also much bigger than you would generally come across. Hand lens for ID would be essential to look at the various branching of the 'filamentous browns'. This does not appear to fit the bill for Spongonema (not filamentous enough). This is probably a mixture as well white weed plus ?
Lat/Lng: 53.3, -3.8
OS grid ref: SH8282