She is a white plesiosaur with pink eyes, potentially showing representation of Albinism . She also carries various inaccurate features, such as a bendy snake-like neck and a long tongue. This long tongue being her namesake (Pero Pero ペロペロ being the Japanese onomatopoeia for licking.)
She is a nice girl and quite understanding of others, not at all put off that Heart was carnivorous (most likely due to Elasmosaurs also being carnivorous). She is selfless as well, since she prevented Heart from drowning.