half square, half circle, an unholy creation of nature only known in the ancient scriptures of Gilgamesh destroyer of world's lair. It was created in 1653 upon the discovers of the seagull sock, a device used by seagulls to house Squircles. to clarify, this is all 100% accurate and you should google it.
"NO PLEASE!!! NO MORE SQUIRCLES GOD MAKE IT STOP!!!!!!!!!!!!!!!!!!"