Since they were first detected 10 years ago, rare and brief bursts of cosmic radio waves, known as fast radio bursts, have remained one of the biggest mysteries in astrophysics.
And the latest fast radio burst, called FRB 150215, might be the most perplexing one yet.
Despite spending the last two years using telescopes to find anything associated with it, researchers have admitted they're still clueless about where this one came from.
Researchers from the Netherlands Institute for Radio Astronomy first detected FRB 150215 in 2015, and have been working since to understand its source.
Speaking to Gizmodo, Emily Petroff, who is leading the study, said: 'We spent a lot of time with a lot of telescopes to find anything associated with it.
'We got new wavelength windows we've never gotten before.
'We're still trying to figure out where this one came from.'
Fast radio bursts, or FRBs, are radio emissions that appear temporarily and randomly, making them not only hard to find, but also hard to study.
The mystery stems from the fact it is not known what could produce such a short and sharp burst.
This has led some to speculate they could be anything from stars colliding to artificially created messages.
FRB 150215 can be viewed through several telescopes, but has not left any detectable signal or trace of light
So far, 22 FRBs have been detected, but astronomers believe that there could be up to 2,000 in the Universe every day.
While astronomers can usually use telescopes to pinpoint the likely source of the burst, FRB 150215 has left the Dutch team baffled.
It can be viewed through several telescopes, but has not left any detectable signal or trace of light.
In their paper, published in arXiv, the researchers said: 'The burst was followed up with 11 telescopes to search for radio, optical, X-ray, gamma-ray, and neutrino emission.
'Neither transient nor variable emission was found to be associated with the burst, and no repeat pulses have been observed in 17.25 hours of observing.'
Adding to the mystery is the fact that FRB 150215 shouldn't have been detectable from Earth given the direction in space it is coming from.
It had to pass through an extremely dense region of the Milky Way to reach us.
The galaxy's magnetic field should have changed the way the light from the radio burst travelled – but it didn't.
Speaking to Gizmodo, Ms Petroff said: 'It probably travelled through some kind of hole in the Milky Way that makes it easy to find compared to normal searches in the galaxy.'
While some have questioned whether FRBs are signs that aliens are trying to contact us.