Turbinweed

Wow - super info, dororeinecke!! Thanks so much.

This is Turbinweed :)

Turbinaria turbinata
(Linnaeus) Kuntze, 1898
This pale brown to grey with dark brown speckles
alga, or Phaeophycaae, can be up to 30cm
long. It is part of the Sargassum family found
primarily in warm waters and in most tropical
seas around the world. It occurs in shallow
intertidal zones, like the reef flats, but also often
found in shallow lagoons with medium to strong
water movement.
Most divers never think about the presence of
Turbinweed until it has broken off and comes
floating on the surface, sometimes mistaken
for something dumped from a marine head or
blackwater tank. The plant is most common on
the reefs around May and June. In the Red Sea
herbivorous fishes and echinoids often feed on
Turbinaria species as they have a relatively low
level of phenolics and tannins. An interesting
fact is that the genus has shown promise as a
way of removing lead from aqueous.
This algae grows mainly in coral rubble and
crevices of the reef for protection from waves
and currents. The Turbinweed has an erected
central stem supporting branches with clusters
of triangular leaves. The pyramid-shaped leaves
are flat or convex topside with spines around.
Its consistency is leather-like and sticky. An
embedded air bubble at the centre of the leaf
tips holds the plant upright.