Some great words for common shapes. This mental_floss post is delightful. There are great images, too, of needle crystals (acicular) and eels (anguilliform). The photo, of my favorite ginkgo leaves (Wikipedia Commons) is flabellate. “Insects with flabellate antennae look like they have two little fans attached to their head. If you prefer Greek roots over Latin, another word for this is rhipidate.”
I know, it’s a word nerd’s dream come true.
(The keyhole image is from A Fanciful Twist.)