There are statues in the Museum and in the Temples.
In the Museum of Olympus (Main Street), get the starfish from the statue of Poseidon. The other statues will teach you about the Greek gods and goddesses, which you need to learn to pass the test by Aphrodite.
In the Temple of the Muses, the statue of Euterpe (muse of music) is in the group nearest the door, on the right side. Get a reed pipe from the free display and she will teach you a song.
(see related question)
Mythology island, on a statue in the museum
Poseidon's statue is in his temple outside to the far left.
It is in the museum, on the face of Poseidon's statue.
From Poseidon's statue in the museum.
In the Museum of Olympus, there is one on the face of Poseidon's statue.
in the underground cavern near Poseidon's statue
The statue of Euterpe, muse of music, is in the Temple of Muses.
The starfish on mythology island is on the face of the statue of Poseidon in the place right next to the balloon when you get on the island.
The statue of Euterpe is in the Temple of Muses. She is among the first eight statues, the first on the upper right.
You click the darker water underneath the statue of Poseidon on the seahorse.
the hydra is in a underground cave near Poseidon's statue.
Yes, she is on Mythology Island, on the path to Mount Olympus. She turns Hercules into stone when he tries to pull her snake hair. (He seems happy enough as a statue, though.)