Here's a corrected version of your sentence:
The brain is wrinkly, like a walnut, and eating nuts is good for your memory, your thinking, and your focus.
Explanation:
- The word "walnut" should not be in all capitals.
- Add commas after "thinking" to separate the items in the list.
- Everything else is great!
Great job noticing the brain looks like a walnut and that nuts help our minds!