Short answers, pulled from the story.
Anaximander introduced the word apeiron to describe the unbounded around 546 BC. This early philosophical concept remained distinct from the rigorous definitions that would emerge millennia later.
Aristotle argued that actual infinity was impossible because it produced logical paradoxes. He drew a sharp line between potential infinity and actual infinity in his writing from 350 BC.
John Wallis introduced the infinity symbol known as the lemniscate in 1655 within his work De sectionibus conicis. This symbol has since been used outside mathematics in modern mysticism and literary symbology.
Georg Cantor revolutionized the study of infinity in the late 19th century by introducing the concept of infinite sets. He demonstrated that there are different levels of infinity and defined two kinds of infinite numbers: ordinal numbers and cardinal numbers.
Giordano Bruno proposed an unbounded universe in 1584 in On the Infinite Universe and Worlds. He stated that innumerable suns exist and innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun.
The Koch snowflake is a fractal curve with an infinite perimeter and finite area. It is an object whose structure is reiterated in its magnifications, meaning it can be magnified indefinitely without losing its structure and becoming smooth.