Help with an ID

[BeachComber7]

I found this on a treasure coast beach (Florida) a while back. It is lightweight, porous underneath and off white in color (as opposed to bright white). I attached several pictures for viewing.

Does anyone know what this is?

 

[poptop]

pizza dough

 

[Fenway]

Is it really light, like foam? If so, could be an old, beat up buoy. I see them all the time.

Maybe some type of sponge?

 

[BeachComber7]

No Fenway it is hard, like stone and not really super light like foam, just lighter than you would expect when you picked it up.

 

[Can Slaw]

Dead Coral that has been tumbled in the surf and made smooth.

 

[seeker41]

looks like coral? post it on some fossil forums and see what they say.

 

[Sandman]

My guess is a urinal cake. I found a round concave one and slid it into my wetsuit jacket for later ID. When my shoulder started to burn I got rid of it. Seems the park managers toss these into the swim area's to ward off algae.

 

[BeachComber7]

Fossil forum is saying it's not a fossil because it's not dark or black. I think it's some sort of fossil. Its not pure white, more of an off white. Thanks for your thoughts.