looks like moss on the rocky reef pools

Size
Height: 5–10 cm
Lifespan
2–5 years
Diet
Photosynthetic. Draws energy from sunlight and nutrients from surrounding water.
Habitat
Grows on rocky reefs in low intertidal and shallow subtidal zones. Forms dense, bushy, branching clumps that look like moss or tiny shrubs, dark reddish-purple to almost black.
Range
Found throughout the North and South Islands on rocky shores, in rock pools, and on other seaweeds. Most common in intertidal and shallow subtidal zones. Also found in temperate regions worldwide.
Endemism
Endemic
Main Threats
None significant. This species is common and widespread. Localised threats include coastal development, pollution, and climate change affecting water temperature.
Population
Not Threatened. Sea moss is common on rocky reefs throughout New Zealand, particularly in exposed and semi-exposed locations. It often forms dense beds in the lower intertidal and shallow subtidal zones.
Conservation Status
Not Threatened
Human Risk
harmless
Handling Note
marine invertebrate, likely misidentified algae leave undisturbed
Conservation Note
Endemic longhorn beetle; not assessed by NZTCS as invertebrates are generally outside the scope of current threat classifications.
Te Ao Māori
No recorded Māori name distinguishes the sea moss from other red seaweeds. It was likely grouped with other red seaweeds called karengo. The bushy dark purple clumps would have been noticed. They looked like the moss of the forest the tiny shrubs of the high country. They were a reminder that the sea has its own versions of the things of the land. The sea moss was sometimes used as a medicine. The stiff crunchy fronds were dried and ground into a powder then mixed with water to make a paste for wounds and skin infections.
The one that looks like it belongs on the forest floor not the rocky reef has fronds that are small branching and densely packed forming bushy clumps that can be 10 to 20 centimetres tall. The colour is a deep reddish-purple sometimes so dark it appears black. It looks like moss like a tiny shrub like a piece of the forest that fell into the sea. It is the alga of the forest disguise the one that pretends to be something it is not. What makes it special is the texture. The sea moss is cartilaginous stiff and crunchy like cartilage or firm jelly. You can bend it but it will spring back. You can squeeze it but it will not crush. It is the bush that bends but does not break the one that is soft enough to flex but tough enough to survive the waves. Under your fingers it feels like rubber like a stress ball like something that wants to return to its original shape. The sea moss is a red alga a member of the Gigartinaceae family. It is harvested for carrageenan a thickening agent used in foods cosmetics and pharmaceuticals. It is the seaweed that makes your ice cream creamy and your toothpaste smooth the one that has found its way into your kitchen without you ever knowing its name. Biologically the sea moss reproduces by releasing spores from specialised structures on its fronds. The spores are released into the water carried by the currents and settle on nearby rocks to grow into new plants. It also reproduces by fragmentation pieces broken off can grow into new clumps. To find sea moss is to find a bushy clump of dark purple on the reef. It looks like moss like a tiny shrub like a piece of the forest under the sea. You can touch it feel its crunchy texture bend it and watch it spring back. It is the moss of the sea the bushy one the one that makes your ice cream creamy the one that proves that the sea has its own forests small and dark and full of life.