Can be damaged or destroyed very easily.
Spiders build their webs to catch prey. But everytime they catch prey the web gets damaged or destroyed and the spider needs to rebuild it again. It's the only creature whose home gets destroyed everytime it catches food. The web can even be damaged by wind alone.
[Quran 29.41] The likeness of those who take to themselves protectors other than Allah is that of the spider. It builds a house. But the most fragile of houses is the spider's house. If they only knew.
How could an illiterate man who lived 1400 years ago have known who has the weakest home?