It’s from the Water
The look of this might make you wary of drinking a glass of water without checking its contents first. Maybe it’s a good practice to live by – always checking what’s inside your glass before taking a sip, and checking your plate before taking a bite. It can be hard when you’re extremely thirsty or hungry, but it’s worth it. This person poured a glass of water at night, and come morning, they woke up to find this inside.
At first, this would be frightening, but it’s a good thing they put it on the internet to find out what it was. There’s no need to think that this is some alien goo or something of the likes; we have a reasonable explanation for you. This is probably the result of something melting and falling into the cup of water, then cooling off and solidifying. Seeing as the water was under a light, it’s not farfetched.