A pencil, quilt block, tiles for the floor, snowflakes, nuts and bolts, honeycomb, chicken wire and soccer ball!
There are no ordinary household objects shaped like a decagon. Some glasses or vases may be decagonal in shape.
There are few household objects that are shaped like nonagons. Some coins in a few countries are, but even these are rare designs.
As far as I know, a hexagon has 6 angles whether it is regular or not. Some may be obtuse angles, but they still count. So a hexagon where some of the sides go 'in' rather than 'out' is still a hexagon.
Objects that are shaped like a diamond include certain gemstones such as diamonds and rhombus-shaped figures in geometry. In chemistry, the molecular structure of some compounds like methane and ethylene can also be described as diamond-shaped. Additionally, some playing cards, like diamonds in a deck of cards, are also shaped like a diamond.
The roof of a house,
A hexagon is a polygon that has six edges and six vertices. Some of the objects at home that are shaped like a hexagon are a Allen wrench, bolts, and a checker board.
Some objects that are shaped like an oval include eggs and footballs.
There are no ordinary household objects shaped like a decagon. Some glasses or vases may be decagonal in shape.
Some examples of irregular shaped objects include rocks, branches, cloud formations, and coastlines. These objects do not have a consistent or symmetrical shape like a sphere or cube.
There are few household objects that are shaped like nonagons. Some coins in a few countries are, but even these are rare designs.
phone
A rubick's cube, an icecube, dice, baby block, some boxes, 2x2 Lego pieces
Objects shaped like a square pyramid are polyhedrons with a square base and triangular sides that meet at a common vertex. These objects have five faces: one square base and four triangular faces. Examples of objects shaped like a square pyramid include the pyramids of Egypt and the roof of some buildings.
The Pentagon in Washington is obviously shaped like a pentagon. Black shapes on soccer balls, some road signs and the home plate on a baseball field are all pentagonal shaped objects.
The water displacement method is used to find the volume of irregularly shaped objects. This method is not necessary for regularly shaped objects whose volume can be easily calculated using geometric formulas. Irregularly shaped objects do not have a straightforward formula for volume calculation, hence the need for the water displacement method.
An octagonal prism is a geometric shape with eight faces that are octagons. Some common objects that are shaped like an octagonal prism include certain types of crystals, such as beryl or fluorite, as well as certain types of nuts and bolts. In architecture, some buildings may feature octagonal prism-shaped elements, such as towers or spires. Overall, objects shaped like an octagonal prism are typically characterized by their eight flat sides and two parallel, congruent octagonal bases.
As far as I ah aware, they are not at all common. Drinks coasters are about the only things that I can think of.