Tiny crab on a washed up jellyfish

[KittenChiu]

At the beach in Florida today and saw a washed up jelly. Upon closer inspection, saw a tiny little movement which I scraped up and put in my seashell collecting bucket. It's a teeeeeeeny little crab. Any ID or idea if it will survive in my (no fish right now) tank? Just wondering for funsies.

 

[SandJ]

Could it be a sea spider? I think they sometimes feed on jellyfish.

I am probably completely wrong, the body looks too big for a sea spider.
Here is an article about crabs living on jellies...
https://blog.walkerinfo.com/blog/cannonball-jellies-and-spider-crabs/