Lobsters grow by molting, a process in which in which they crawl out of their old shells while absorbing water which expands their body size. After molting, lobsters consume more than normal to increase their growth size and to bring calcium to their blood stream which can subsequently help harden the shell. Molting happens about 25 times in the first 5-7 years of life until they are one pound. After this, male lobster will molt once per year and female lobsters twice. At this point, with each molt the lobster will grow about 15% in length and 40% in weight. A lobster's age cannot be determined exactly; However, based on scientific knowledge of body size at age, the maximum age attained may approach 100 years (see experimentation).