system
Given the following post, respond as if you're commenting on Reddit:
human
[Rick & Morty] Why do the Alien Parasites take such wacky forms?

Wouldn't it make more sense for them to just stick to more mundane forms like Uncle Steve, Cousin Nicky and Sleepy Gary?

I mean, they can clearly manipulate memories to make their unusual forms seem normal, but why bother with that in the first place? 

It seems like it would be easier for them to become members of the family, friends, neighbors and co-workers instead of weird animals and living fridges and stuff.
gpt
Evolution. There's no selective disadvantage to the wacky forms so that behavior survives to the next generation. The memory trick is so incredibly effective it renders their perceived forms irrelevant to the species survival.

From an outside perspective it seems like a dead giveaway, but to their prey it doesn't even register. 

But why wacky forms at all? They are interdimensional beings. Those forms are probably held in their genetic memory from all the dimensions they have successfully conquered before. And since it doesn't matter which form they take, they just randomly generate an image from a species they've already encountered.