Notes on crystal binding proteins
I’ve had trouble finding info. A google search on “crystal binding proteins” sorta worked.
IgA binds to cholesterol crystals:
Cholesterol crystal binding of biliary immunoglobulin A: visualization by fluorescence light microscopy. Lammert et al. World J Gastroenterol. 2001 Apr;7(2):198-202.
There no doubt are proteins that bind to calcium carbonate shells material, but I couldn’t find info on them. I think shell is formed like bone, by cells increasing the local concentration of Ca++ so it crystallizes out of solution rather than by direct enzymatic action.