When biology students at the University of Southern Denmark were asked to tag starfish for identification, it seemed like a pretty straightforward task; scientists use tags to track animals all the time. There was just one problem: The injected tags kept somehow coming out of the starfish.

As it happened, the two students had discovered a new self-healing mechanism. Starfish can squeeze foreign objects out of their bodies, according to their study.


The pill-sized tags were injected into the bodies of the starfish. Using magnets and sonograms, the students found that, over the course of a few days, the starfish moved the tag through its body cavity without harming any internal organs before finally squeezing it out through the skin at the tip of one of its arms. “It came out directly through the skin; the starfish simply pushed it out through the skin at the end of one arm and then went on as if nothing had happened,” they explained in a press release. 

Skip to about the one-minute mark in the video below to see it in action: 

It’s sort of the equivalent of getting shot in the stomach, and having the bullet just make its way casually out your arm. No big deal.  

[h/t: Eurekalert]

All images courtesy the University of Southern Denmark