WireWeed
Where to find wireweed
Wireweed lives on the lower shore or in shallow sub-tidal waters but it may also be seen in rockpools on the middle of the shore. It usually attaches to rocky substrates such as bedrock, boulders or small stones but it can also be found attached to shells. Wireweed can be found on a wide variety of shores but generally prefers those with a bit of shelter from wave action. Wireweed commonly becomes detached and will float away (this is one of the reasons it spreads so quickly) and consequently it may also be found floating in clumps at sea or washed up on the shore.

Sargassum in the wild