It’s Halloween, and scientific organizations are taking to Twitter with their scariest images. From spooky-looking rocks, to a ghostly octopus, to the sun taking on the appearance of a jack-o-lantern, here are some of the most haunting science images of the day.

Two years ago, the Solar Dynamics Observatory spacecraft imaged the sun looking pumpkin-like. No candle needed.

The swirling patterns of the aurora borealis over Selfoss, Iceland look strange in an image, taken in 2015, that the European Space Agency tweeted.

The Bureau of Land Management did their best to spook people with a shot of a monster caught in stone. Truly petrifying.

Then there are lots of cute, creepy critters to be found under the sea. NOAA Ocean Explorer has been tweeting out images of an adorable, Casper-like octopus, a “ghost fish” first seen in July, and even a frog fish that resembles an undersea pumpkin.

 The Smithsonian got in on the fun, too, with some dancing skeletons. Bare bones, indeed.