A Septagon from the greek Sept meaning 7
An L shaped figure is a plane figure and so will not have a volume.
An ellipsoid is a three-dimensional egg-shaped figure.
A star shaped figure is described as stellate. Also a hexagram
an inverted kiteIf it is a quadrilateral then an arrowhead. Otherwise simply call it arrow-shaped.
method usede to figure the volume of an irregular shaped object
No, the sun is not a plane figure. It is a 3-dimentional astronomical object we call a star. Plane figures have just two dimensions.
A hexagram
A circle. An ellipse. There are lots of fancy shapes as well like a cardio (heart-shaped curve), a limaçon, a lemniscate, and so on.
A seven sided figure.
A circle perhaps
Assuming the question is about a 15 sided figure rather than a 15 shaped figure, it is most commonly known as a pentadecagon, less so as a quindecagon, and even less familiarly as pentakaidecagon.