The Hippocampus is a glamourous animal of the ocean. They were the pets of the sea and horse god, Poseidon and would draw his chariot across the sea. They have the upper-half of a horse and the lower-half of a fish or dolphin. They love being out at sea and are fairly strong creatures with lots of stamina. They are devotional to their god and like to spend time with their fellow Hippocampi.
A dryad is a tree nymph, that is a female spirit of a tree, in Greek mythology. In Greek drys signifies "oak". Thus dryads are specifically the nymphs of oak trees, though the term has come to be used for all tree nymphs in general. They were normally considered to be very shy creatures, except around the goddess Artemis, who was known to be a friend to most nymphs.
Mnemosyne, Greek goddess of memory, was considered one of the most powerful goddesses of her time. After all, it is memory, some believe, that is a gift that distinguishes us from the other creatures in the animal world. It is the gift that allows us to reason, to predict and anticipate outcomes, and is the very foundation for civilization. When she is remembered it is usually only in the context of her being the mother of the Muses. Her parents were the rulers Cronus and the goddess Gaia.