types of pyramids:

there is also a clasification of piramids :

Regular: 
The base regular pyramid has a regular polygon and its sides equal                                                                                    

 Irregular:

The irregular pyramid base is an irregular polygon.

Convex:

is the pyramid that has a convex poligon in the base it means that the angles of the poligon measure more than 180°

 

Concave:
 is the pyramid that has a concave poligon base it means that some of the angles mesure less than 180°

 

Straight:

 is the pyramid that has a right angle

 

Oblicue:

 is a pyramid that one of its sides is an isoceles triangule

Square:

 the base is an square

 

Trinagular:
the base is a triangle

Pentagonal:
the base is a pentagon

Hexagonal :
the base is an hexagon