Horseshoe crab
From Tardis Wiki, the free Doctor Who reference
Horseshoe crabs were an advanced species that referred to themselves as the Creators, the Armourers, and the guardians of the great oceans between the stars. Their genetic engineering technology was far in advance of that of humanity. In the past they inserted genes into the human genome for their own purposes. (PROSE: The Southwell Park Mermaid)
