A Klein Bottle is a mathematically brain-melting object with no in or out and no front or back, and thanks to Wizard Gynoid, one of them was made to float in Second Life. Watch this machinima to see what I mean:
Love the music by modern master Moby and metaverse artist Miso Susanowa, and it's a credit to both I can't tell when the Moby music ends and the Miso music begins. (Or vice versa.) Via Second Life's Subreddit.
This isn't the first Klein bottle to rise from SL, as I suggested: At least one more was created in 2008 by AM Radio and Miki Gymnast.
Via Ms. Gynoid in Comments: Click here for a direct teleport SLurl to the Klein bottle.