Cephalopods
Cephalopods are the only groups of mollusks without shells on the outside. Their shell is on the inside and is called the pen. Cephalopods are the most interesting of mollusks. One reason being that they can fit into spaces one-tenth the size of their body. The second reason being that they can change the color of there skin extremely easily, as shown below in the video. Cephalopods have to protect them self, right? Most cephalopods have ink and tentacles and they protect themselves that way. But ther is one unique octopus can kill you with one bite. The blue ring octopus, shown above on the right, is the most toxic cephalopod. -er