Leaders of the largest search for the Loch Ness monster in 50 years said they heard several distinctive sounds over the weekend that may have been made by the mythical creature—though they forgot to plug in their recording equipment to capture the noises for posterity. Hundreds of people from across the world travelled to Scotland last week to hunt for the beast in a mission known as “The Quest,” according to the The Loch Ness Centre, which partnered with voluntary research team Loch Ness Exploration to sponsor the event. Among the new additions to the search were new technologies like thermal drones, which had never been used in the loch. On Sunday the Centre announced that teams returned to the area where “four very distinctive noises,” described as “gloops,” where heard on Aug. 25 while surveying the loch. At the time they admitted that the researchers “hadn’t plugged that [recording device] in...which is typical. Typical.” Their return Sunday marked disappointment, with organizers confirming that “the sounds weren't found again. Their source is as yet undetermined.” Meanwhile investigators are assessing video footage from two volunteers of “something unexplained” in the water on Sunday morning.