Iron in Breakfast Cereals: Absorption & RDA Concerns

Question
My children and I have extracted iron shards from some breakfast cereals and we wondered if these particles are absorbed and used by the body. Are the cereal companies claiming there is 100% RDA of iron when some of it cannot be used by the body? What is the name of the iron that our bodies do utilize?  Thank you for your time.

Answer
There are two kinds of iron found in foods; haem from animal products
which is readily absorbed by the body and non-haem from plant
sources,which has a slightly different chemical structure and is less
easily absorbed. This non-haem is the form of iron added to
iron-enriched and iron-fortified foods. However this form of iron is
treated in such a way that its bioavailability is significantly
improved, howeverI wouldn't suggest relying on fortified cereals for
your iron RDA.