Colonies can join together to form large mats that cover everything from rocks to boat hulls to other marine organisms, frequently killing native plants and animals. It is very invasive, as demonstrated by its rapid growth along both North American coasts.
The star is believed to be a native of Europe that somehow made its way to the East Coast a few decades ago, probably by clinging to the hull of a ship. In the mid 1940s it was discovered in San Francisco Bay and has since been found from Baja California to British Columbia.
But while it may be a nuisance to some, it seems destined to be a hero to others. That role was foreseen by Charles Darwin in the mid 1800s.
Darwin thought these odd but fascinating creatures might help us understand how life evolved to include vertebrates, like us.
That doesn't seem all that far out, now that we know we share so many genes with a distant relative most of us never knew we had.