Maybe! That doesn't look like it would work though. A fish would have to be really dumb to mistake that for coral.

[Nagisa shakes his head, rolling over before slipping off the rock and back into the water. He pops back up a second later, shaking his head briskly.]

Anyways, that's pretty much the kind of stuff that washes up on the beach all the time. Pretty weird, but some of it is cool!