Laragasiphon major is very efficient in taking up calcium and will deposit it via the leaf surface, where it collects. Not sure if any other plants do this though.
Edit - just thought, I have seen calcium deposits on Egeria densa at work recently.
All plants need calcium for cell structure and other functions, but excess can cause problems, so it stands to reason that in water with high calcium content, excess will be ejected by the plants, perhaps this is happening with your Anubias. Is your water particularly hard?
If this is the case, then your plant is obviously dealing with the problem, but to prevent possible damage, it may be worth mixing some RO water with your regular supply to reduce the calcium levels.... or add more plants, which will take up more calcium.