The prickly pear
The cactus that grows wild on cliffs beside the Mediterranean is most likely a species of opuntia, or prickly pear. They are made up of what look like oval plates, jointed together in series, and covered with spines. They have pretty bright-yellow flowers.
But this is where their pleasant side ends. They do have ‘normal’ cactus spines, but they also have masses of tiny barbed hairs called glochids, which are almost invisible, and get into your skin and cause prolonged painful irritation.