Sponges can be very abundant in some sedimentary rocks but in many others they are rare, overlooked, or represented only by microscopic spicules. Siliceous sponge spicules were the source of much of the silica which now forms flint bands and nodules in the Chalk (Ulster White Limestone), or chert bands in the Carboniferous Limestone.

In Northern Ireland sponges are sometimes abundant near the base of the Ulster White Limestone Formation (Upper Cretaceous; 100-65 million years ago), particularly in the Cloghfin Sponge Beds of east Antrim. The Ulster Museum has extensive collections of Cretaceous sponges from Northern Ireland and from further afield, much of the material donated by Dr. R.E.H.Reid. A selection of the more common or conspicuous types are included here.






















Rhizopoterion cribrosum

Rhizopoterion tubiforme


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