[9] The color of the thallus is greenish when exposed to ultraviolet light, but when it grows in deeper water it is darker red to purple.

[2] Though it prefers lower water temperatures it can grow at 25 °C, but ends up dark red to black in color and having flat or cylindrical branch clusters.

[10] As originally described, C. exasperatus has a leafy stipe, with large 2–3 feet (0.61–0.91 m) long leathery-membranaceous blades that are lanceolate and simple.

[11] It grows on rocks in semi-exposed or semi-protected areas of the upper subtidal to lower intertidal zone,[7] down to a depth of 20m.

[15] The high rate of decomposition also means that it is harder to find washed ashore as wrack and that its importance in the ecosystem may be underrepresented in research.

[15] The isopod Ligia pallasii[17] and the green sea urchin (Strongylocentrotus droebachiensis)[15] also seems to prefer to eat other seaweed species.

A diet of C. exasperatus can slow or decrease shell length in juvenile white abalone (Haliotis sorenseni) at extreme water temperatures, and possibly can be deadly at 18 °C or above raising concerns related to global warming.

[20] Intact blades are used in baths or for thalassotherapy, along with species such as feather boa (Egregia menziesii), finger kelp (Laminaria digitata), and Fucus.