Agate question

I am finding a lot of similar looking ones and am a little curious as well.

Yes, openings in the ground get filled by rhythmic crystallization from the exterior to the interior as happens in fortification agate.

You can often follow the progression from empty hollow to last layer to be formed in what becomes the center.

SE US coral is silicified by mineralized water, just like chert. Chert is often full of fossils, coral no different, just a big fossil and receptor of silica rich water
Coral dense and hard like chert. Root holes(casts), clam holes(casts), death plate(chert) all are found hand in hand with coral. Same cast material.
Some coral cast, some replaced, some are hybrid. Indonesian coral replaced much better than SE US coral. So the corallite preservation.

Chert is mined for highway gravel in Florida. A quarry will have 20 foot boulders of dead pure (not-so-pretty) chert.
Chert deposits are massive in thickness. They blast and crush those big boulders into road gravel.
They are glassy enough to be very vulnerable to dynamite. Much of it chips/breaks conchoidal.
and it is wet inside. Wet enough that fire will make it fracture to little pieces and fragments.
Takes a year in a greenhouse to dry it out when the size of a brick. Longer for soccer ball size.

Many of the gravel roads in central Florida are paved in a boring devil's toenails type chert gravel. Very fossiliferous.
Some coral locations have iron deposits effecting the color. Most do not. I think the salt dissolved a lot of the iron as you move into Florida.
Lots of Georgia coral is stained on the outer layer from iron, Iron from iron rich clay that washed down from the Appalachians.

Most coral and chert down south has never seen a freeze, protected by ground warmth or rivers.

Awesome jamesp