If you guessed fish, you’re right! Did you need a figure caption to tell you it was a fish? I don’t think so. That’s why a figure caption like this one isn’t very helpful:
An x-ray of a cartoon character’s brain.
This caption just tells you what you can already see- this is an x-ray of a cartoon character. It doesn’t offer any new information. When you’re writing your figure captions, try to add useful descriptions. Here’s another try at describing the same figure:
A 27-year-old male cartoon character with microcephaly.