- Huckle: Doctor, do you mind telling us exactly what you're doing?
- Doctor Who: A little experiment in orthodontology, Mr Huckle.
- Huckle: Orthodontology?
- Doctor Who: Teeth. Teeth. The scientific study of teeth.
- [Holds up the plaster cast]
- Doctor Who: That's that cast of a tooth, wouldn't you say?
- Huckle: Teeth? Doctor, you can't be serious.
- Doctor Who: Teeth are very serious things, Mr Huckle.
- Huckle: Look, let's get this straight, are you saying those rigs were chewed up by a set of giant molars?
- Doctor Who: Yes. A set of giant molars that can chew through solid steel as easily as paper.
- Brigadier Lethbridge Stewart: Are you suggesting that we're dealing with some kind of sea monster?
- Doctor Who: Yes. A monster of frightening size and power.
- Zygon: This one they call "Doctor", is a threat to us. Already he has found out too much. He must be... destroyed.
- Doctor Who: [the Doctor and Sarah are trapped inside the decompression chamber] What's that noise?
- Huckle: I don't know, but it's not the air conditioning.
- Doctor Who: Brigadier, Brigadier! Have you brought me 270 million miles just to sort out a little trouble at sea?
- Brigadier Lethbridge Stewart: Three serious disasters, Doctor... .
- Doctor Who: When I left the Sionic beam with you, Brigadier, I said it was only to be used in an emergency.
- Brigadier Lethbridge Stewart: This IS an emergency.
- Doctor Who: Oil? An emergency? Hah. It's about time the people who run this planet of yours realize that to be dependent on a mineral slime just doesn't make sense. Now, the energizing of hydrogen... .
- Brigadier Lethbridge Stewart: Doctor, the destruction of these rigs is a complete mystery. Do you want more men to die?
- Doctor Who: No. Very well. When do we start?
- [on oil]
- The Doctor: It's about time the people who run this planet of yours realized that to be dependent on a mineral slime just doesn't make sense.