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.
A star shaped figure is described as stellate. Also a hexagram
A 15-sided figure is called a pentadecagon.
A seven sided polygon in called a heptagon.
pentegon
An L shaped figure is a plane figure and so will not have a volume.
An eight sided shape is called an octagon.
An ellipsoid is a three-dimensional egg-shaped figure.
It is a pentadecagon or pentakaidecagon, sometimes simply called a 15-gon.
It is a bit like a circle with a curved tangent emerging from it. Not sure that it has a name!
There is a musical instrument called a triangle, it is both shaped, and named, the same as the three-sided figure itself.
Some synonyms for star-shaped figures include asteroform, stellate, stelliform, astromorphic and multi-pointed. Star-shaped figures could also be described as polygons.
method usede to figure the volume of an irregular shaped object