Madracis auretenra is a common coral in the Caribbean which until 2007 used to be called Madracis mirabilis. Colonies form dense hemispherical clumps that can be several metres across.
The ends of each branch are covered in living tissue but it is common for the lower portion of the branch to have no living tissue and only hard skeleton. This is a unique feature of Madracis auretenra. As the coral grows living tissue recedes from lower branches leaving tissue only on the branch tips.
Yellow Finger Coral
This coral is always bright yellow with finger like branches which is why the common name for this coral is the Yellow Finger Coral.
The size of the branches depends on where you find this coral. In shallow reef with current, the reefs are thin which deeper colonies with have thick robust branches. In deeper water, the branches will be tightly clustered so you may not be able to see the lower bare branches.
When you find one colony of Madracis auretenra there is often more! This coral grows into small clusters and broken branches can form new colonies adjacent to older clusters. You can find this coral from 3 meters down to 50 meters pass recreational diving limits.
You should not confuse this coral with Madracis decactis, the Ten Ray Star Coral. Both are yellow and have characteristic star shaped corallites with polyps that extend above the surface of the colony. The difference is Madraci decactis forms short stout branches with rounded tips, Madracis auretenra forms long slender finger like branches.