Unidentifiable Sea Creature

[MTbowels]

I've inherited a number of dried sea animals such as a starfish, sea-horse and a number of unusual shells. One of them is baffling me as far as identification is concerned and I wonder if anyone could help in identifying it.

It looks almost identical to a large cap of a mushroom that has been turned inside out i.e. the gills are on the upper surface rather than the lower. Just like a mushroom, the gills radiate from the peak to the edge and oddly enough are spaced about the same distance apart as you would see on an upturned large mushroom cap. The upper surface is snow-white in colour whilst the underside is a sort of dirty white. The texture on the underside feels like sandpaper and contains many small, sharp nodules that are hardly visible.

The whole thing is about 150mm diameter with an apex height of 80mm. The thickness of the object is about 15mm at the edge.

I was thinking it might be some form of urchin but I'd be grateful for any comments. I know from when I was young that dried sea creatures such as these were readily available at seaside promenade shops, so I suspect it's a few years old

Thank you.

[MTbowels]

Oops, sorry I didn't mean to imply that the object was a shell. Must read my posts before posting!

[mccfluff]

could it be an alfonso sea urchin (loads to look at on this site if not the right ones

http://ep.yimg.com/ay/yhst-48699173286383/alfonso-sea-urchin-7.jpg

http://www.atlanticcoralenterprise.com/ProductCart/pc/viewPrd.asp?idproduct=29359&idcategory=44

[MTbowels]

Thanks mccfluff but I'm afraid none of them resemble what I've got.

Mine looks exactly like a six inch mushroom cap that has been turned inside out and is pure white in colour. I suppose it may have been bleached but I can't imagine why. There are no patterns evident amongst the "gills" and certainly no variations in colour. The whole thing looks quite fragile. The individual gills look around the same same thickness as what you'd find on a mushroom so it's very delicate.

Thank you again.

[Prudie]

I'd suggest it was a mushroom coral, google some images.

[woofgang]

can you put a photo on tinypic and post a link here?
could it be a sand dollar?

[Answerprancer]

This?
https://en.wikipedia.org/wiki/Fungia

[MTbowels]

It's a Fungia!! It looks exactly like the thumbnail at the top of the Wikipedia link.

Thank you all for your help. I'm immensely grateful.