Like all known Placodonts, Paraplacodus was an aquatic reptile that fed almost exclusively on shellfish. Most known Placodont species can be divided into two groups - the unarmored placodontoids, which would resemble a large, scaly, tooth-filled newt, or the armored cyamodontids, which would resemble a heavily armored turtle; Paraplacodus would have been in the newt-like family, but grew to a length of 1.5 meters (4.9 feet).