"As with all species of Petalifera and Dolabrifera, it has numerous papillae on its back that can be either extended and then they are quite easily visible (as in this photo), or retracted and then they are invisible."
Comment from Richard Willan
As with all species of Petalifera and Dolabrifera, it has numerous papillae on its back that can be either extended and then they are quite easily visible (as in this photo), or retracted and then they are invisible.