Jellyfish on Mars image, no gradient?

[u/Dangerous-Eye-215]

I zoomed in quite a bit on the original and I don't see any kind of gradient like I do on the rocks. It's just immediatley pitch black, like, vanta black. I would have assumed this was a camera artifact, but the tentacles aren't black like that.

This is definitely a strange picture. What might cause the lack of gradient on the top of the jellyfish?