Mew Power Pendant

The Mew Pendant helps the girls to transform into their Mew Mew forms. It first appeared in episode 1 of Tokyo Mew Mew (Volume One of the manga series) where Ryou gave it to Ichigo to fight the Chimera Animal, and in Chapter one of An Unnatural Day, when Amy and Anna acquire one each. Kissing the pendant is required to trigger the transformation. Another requirement to make it work is to call the transformation phrase "Mew Mew -insert name-, Metamorphose!" The pendant is seen on all mew mews, dangling from their chokers.

Trivia

 * The Mew Pendant is just a tool to aid the transformation process. It's also shown that transformations can happen without the pendant's help if any of the girls' emotions run high, Lettuce being an example in the official series whilst, in an Unnatural Day, Peach and Melon both transform without pendants too.
 * The Mew Pendant can also be used as a communicator.
 * The pendants shrink when they're on the mew mew's chokers, as shown when the girls hold them; they fit into the palms of their hands, whilst when on the chokers they're much smaller.