After identifying the 23,300 genes of the Strongylocentrotus purpuratus, the California purple sea urchin, genome, researchers found humans shared 7,077 of their genes with the arguably different-looking brainless and limbless invertebrate.
The genetic ties were far closer than scientists had expected and make the sea urchin a closer genetic cousin of man than the worm or fruit fly, the study in the journal Science found.
"I've been looking at these organisms for 31 years, and now I know they were looking back at me," said Gary Wessel, a Brown University biology professor and member of the Sea Urchin Genome Sequencing Consortium.
"Nobody would've predicted that sea urchins have such a robust gene set for visual perception," he added.
Researchers also found that sea urchins have the most sophisticated innate immune system of any animal studied to date -- one reason they live 100 years or more.
They carry genes associated with human diseases such as muscular dystrophy and Huntington's disease.
The sea urchin also has genes associated with taste and smell, hearing and balance, the study found.