Hitch hiker I'd. Could not find it on lionfishlair

Sorry doing this on my phone and it will not let me upload a picture. It almost looks like a baby brittle star but it only has 3 tentacle and moves round on the glass. I have managed to get it out and into a bowl but don't know how long it will last in there. Any help will be grate and I will try and upload the picture when I get home