We all know what icebergs look like, don't we? Pointy white lumps bobbing about in the sea, with lots more ice under the water.
Apart from in the case of this mind-boggling "tabular" iceberg captured on camera by Nasa's Operation Ice Bridge, floating amongst the ice just off the Larsen C Ice shelf.
Theories posited by Twitter users included "it was aliens", but there's a simple scientific explanation. Watch the video above to learn more.