Egg (robin, ostrich, chicken, lizard, crocodile, turtle)
Leaves (Beech, birch, hornbeam, alder, juneberry, elm, witch hazel, dogwood, mint)
Seeds (pumpkin, wild cucumber, beans)
Fresh water pearls
Tanning salon eye protectors
Some buttons on phones, fax machines, etc
Dining room table
Vitamins (cod liver oil, multi vitamins, Vitamin E)
Sun glass lens
The bowl of a spoon
M & M peanut
Tear drop, ovate, ovoid, elliptic, prolate, loop, almond-shaped
Describing a shape is best done in as few words as possible. Think of the shape as a camera snap shot--you want to capture the gist of what you mean as soon as possible so you can get on with other related (and more important) detail, and the action happening in the scene
A weak example:
After adjusting my snorkel mask, I lowered my head into the blue-green water. All along the pier, schools of colorful fish lazed about, hiding from the Caribbean sun. Up ahead, a particularly ugly fish caught my attention--an oval shaped thing with fat, grey lips and wicked looking teeth. It hid underneath something the same size as it, which I figured must be the foot of another hotel guest sitting on the pier above with his legs dangling into the water. I surfaced to warn him what lurked beneath the bottom of his foot and ended up choking on a mouthful of salt water. The only thing in front of me was an anchored rowboat, about seven feet in length. An image of the monster's knife-sized teeth ripping through my wetsuit sent me flailing backwards, away from the boat and the freakishly huge fish beneath it.
What's wrong with this example?
The description is a bit long and rambly, which steals a bit of the punchline--a fish the same size as a row boat. Tighter description along with a more specific image than 'maybe a guy's foot' will bring more oomph to the twist at the end.
A strong example:
The amber pendant hung against the hollow of her throat like a glistening drop of honey.
Why does this work?
The description here is economical and offers a concrete image of both color and shape.