Coral or something else?

[Khyssa]

My friend found this on Honeymoon Island, near Tampa, Florida. We've both found plenty of fossil coral there in the past but this particular piece has us stumped. At first we thought it was coral but on closer examination it doesn't seem to have the right structure to be coral. There is the possibility that this could have come from somewhere else as people have found old ship balast stones in the Tampa Bay area in the past.

The measurements are in inches.

[Khyssa]

Here are some close ups of the rocks structure. I took the pictures from several differnt places on the white portion of the rock. I think my phone attachment does 30x or 60x magnification, can't remember which at the moment.

[TqB]

Certainly not a coral, looks like a sponge.

[Guguita2104]

I agree with Tarquin, Khyssa.

[Khyssa]

Thank you. I hadn't thought of sponge since this has a much bigger diameter then any fossil sponges I've seen before. I don't think I've ever found a fossil sponge over 2" in diameter.