Hi,   I always struggle to tell the difference between a Plesiosaur tooth and an Ichthyosaur tooth. This tooth comes from Goulmima in Morocco (lower Turonian) so I believe it is a Plesiosaur tooth (possibly a Pliosaur tooth), but wanted to confirm it here. The tooth is 4.2cm in length and retains the ridges on the tooth which I think is how you might tell the difference between Plesiosaur and Ichthyosaur. Thank you!