1. Mutualism ~ When both organisms benefit.
Egyptian Plover and crocodile
2. Commensalism ~ Only one organism benefits but the other remains neutral
Bird nest and Tree
3. Parasitism ~ Only one organism benefits and the other is harmed;
Dog and Ticks
C. were conditioned to salivate in response to the sound of a bell.
The most likely way is that it is from the mantle and got pushed up to the air and cooled down into a rock