Excuse me, what is the coffin in Feng Shui? What are the characteristics of the terrain?

In Feng Shui, it is unlucky to have a coffin, especially when choosing a house. Coffin land has two characteristics:

1, a strip feature, that is, it is 2~3 times wider.

2, it is not a rectangle, but a big head and a small head, like a trapezoid.

It looks like a coffin.