It is also resistant to naturally occurring biodegradation processes. It is the sweetest of all naturally occurring carbohydrates. Calcium is sometimes a constituent of naturally occurring amphiboles. Phosphate deposits can contain significant amounts of naturally occurring heavy metals. There are a number of food ingredients that naturally contain caffeine. Seaborgium has no stable or naturally occurring isotopes. Nihonium has no stable or naturally occurring isotopes. Copernicium has no stable or naturally occurring isotopes. Roentgenium has no stable or naturally occurring isotopes. Meitnerium has no stable or naturally occurring isotopes. Darmstadtium has no stable or naturally occurring isotopes. Rutherfordium has no stable or naturally occurring isotopes. Hassium has no stable or naturally occurring isotopes. Chitin is one of many naturally occurring polymers. Many commercially important polymers are synthesized by chemical modification of naturally occurring polymers.