What is this meme based on? I’m out of the loop

I love Greenland sharks.

True, the last Greenland Shark I got for Christmas turned 300. I wasn’t prepared for it and wasn’t in the right live stage but I kept to this commitment

I know it’s so sad that in the spring and summer many people who got them for Christmas and don’t wanna take care of them anymore just let 'em go and I see 'em swimming all up and down the rivers. Poor things.

On the plus side, they’re low-efford. Just let them roam free and they can feed themselves (native ecosystem only).