Giving cells a tough calcium phosphate mineral coat can make them much more robust, Chinese researchers say.

The team has developed such egg-shell-like coats for yeast cells that let them survive longer in harsh environments, entering a state of “suspended animation,” where they did not grow or divide. When the shells were later removed with a weak acid solution, the cells began growing and dividing as normal.

Incorporating iron oxide particles into the shells made the cells magnetic, making them easy to move around using magnets to target cancer drugs.