I’ve been very perplexed by this Florida fossil whether it’s a coral or sponge, but my sense of curiosity doesn’t give up easily. Follow along as I come to a conclusion as to its identity. To begin with, the mystery fossil possesses meandering ridges resembling the various types of brain corals, yet it is dotted with numerous protruding openings very much like the encrusting sponge species below, also in Florida.
The problem with the encrusting type of sponge is that they cover hard surfaces much the same way in which moss covers the ground. I don’t know if this type of sponge, with its unique growth pattern, would break loose and end up on a beach where my mother-in-law, Winkie, picked it up in Florida during the 70’s and 80’s.
If you’ll notice, the “rose brain coral” above has a few pitted holes like the mystery fossil but not nearly as many; and if you’ll also notice, the “pink lumpy sponge” to the right possesses a pattern of ridges, but only sort of like the mystery fossil. Hmmmm . . . a point I’d like to make for a second here, is how this demonstrates what fossil hunters do. They learn to observe things with a keener eye in order to identify their findings. Anyway, we’ve concluded our mystery fossil has similar characteristics as the above corals and sponges, but not exactly the same as any of them.
We’re on the bloodhound trail, let’s continue observing. On the one hand, the mystery fossil is quite lighter and airier compared to the other Florida corals in my collection and it has more openings visible on all sides which leads me to think it could be a sponge. But, the patterns of ridges, plus the color, shape, and texture is quite similar to the other corals from the collection.
So, if the mystery fossil, on most levels, appears to be a coral with the one exception of the deeply pitted holes, what could have caused those holes and why so many? Observe the Christmas tree tube worm image above. The tube worms have completely covered the top of a coral. Could they have made the holes in question? I’ve decided not because the openings on the mystery coral look quite different from the tube worm burrowing on the clam fossil above. I’m no expert, but I decided the mystery fossil is a type of coral, likely related to the brain corals. Feel free to disagree in the comments if you know of think otherwise.
Check out the tube worms link to the right listed under CLASSIFICATIONS to learn more about them and how they can actually be quite pretty.