Here is the tongue coral just after it arrived. It too has a bony skeleton, covered with small polyps. A snail can be seen on the lower left, and a partly expanded button coral at the top.
Here is a close-up of the tongue just after I received it. The polyps are very small indeed. A button coral can be seen in the background.
Fully expanded polyps make the shape of the underlying skeleton almost impossible to see: this is a happy coral!