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.

Happy Halloween! Our sun looks a bit like a spooky jack-o'-lantern in this image from sun-watching spacecraft SDO: https://t.co/L5llu3HiJZ pic.twitter.com/TRC9QlhWJL — NASASunEarth (@NASASunEarth) October 31, 2016

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.

Boo! Monstrous rock formations appear on your public lands! Happy Halloween 👻🎃 https://t.co/T8TMtMdhHi pic.twitter.com/4EXv3v3KAr — BLMNational (@BLMNational) October 31, 2016

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.

Happy #Halloween from “Casper,” the friendly ghostlike octopus! Seen on #Okeanos expedition off Hawaii, it is likely a new species! pic.twitter.com/JFnrr6GWsi — NOAA Ocean Explorer (@oceanexplorer) October 31, 2016

This “ghost fish” was seen while exploring in Marianas – was 1st time a fish in this family was seen alive! #HappyHalloween! pic.twitter.com/5y5Ao0CjvN — NOAA Ocean Explorer (@oceanexplorer) October 30, 2016

A frog fish that kinda looks like a pumpkin, as we head towards #Halloween...! #OkeanosExplorer pic.twitter.com/DjAnVjy92T — NOAA Ocean Explorer (@oceanexplorer) October 29, 2016

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

Follow Rob Verger on Twitter: @robverger