Density can be calculated by dividing the mass of an object by its volume. Water has a density of 1g/ml. If an object’s density is greater than 1 g/ml it will sink and if its density is less than 1g/ml it will float?

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later