The Brain Cactus, aka Mammillaria elongata 'Cristata’, is a wildly unique plant and gets its name from its very evident brain-looking growth, which is a result of damage to the plant when it is young. The cells of the injured area start multiplying rapidly, which causes the pads of the plant to twist. Although they are not poisonous, watch out for their sharp spines! Cacti are a great starter plant or gift as they need very little water and will thrive in full sun. They would much rather be too dry than too wet (think of desert conditions when taking care of them).