Most disappointing Livestock Purchase?

[whatcaneyedo]

I was a bit disappointed with the 1/4" $30 aptasia eating nudibranch that I bought. It simply disappeared after 2 days never to be seen again. However I should have set it up in a QT tank with some aptasia covered rock and allowed it to grow to a more realistic size before adding it to my display. Actually I should have bought and did that with several but the little things were pretty expensive and I didnt think they would solve my problem anyways.