calcareous sponge spicules

[Deb in Michigan]

I have read that finding spicules preserved in sponge is quite rare.  I am finding sponge fossils with what I believe are spicules, but the fossils seem to be all calcium carbonate, no silica. 
this seems to me to show the original sponge body was aragonite or calcite based.  This was found on the north eastern side of the tip of the Mitt in Michigan  The area is considered Middle Devonian, but these were found on the shore of Lake Huron, so there is also the possibility that they are glacial transports.    Comments welcome. 

[Deb in Michigan]

spicules seem to be monaxons and triactines for the most part, with some odd shapes rarely interspersed.  Specimen is approximately 6 inches by 5 inches by 5 inches.  Leucon form,  I wonder if what i am seeing is also preserved spongin.  So many questions!  

 

[Deb in Michigan]