Mystery solved on 500 million-year-old squid creature.

I'm pretty sure H.P. Lovecraft has already explained this creature. From One India:

A research by Canadian palaeontologists has shed new light on a hitherto unclassifiable 500 million-year-old squid-like carnivore known as Nectocaris pteryx.

Martin Smith of University of Toronto's Department of Ecology and Evolutionary Biology (EEB) and the Department of Natural History at the Royal Ontario Museum (ROM), said: "We think that this extremely rare creature is an early ancestor of squids, octopuses, and other cephalopods.

"This is significant because it means that primitive cephalopods were around much earlier than we thought, and offers a reinterpretation of the long-held origins of this important group of marine animals."

The new interpretation became possible with the discovery of 91 new fossils that were collected by the ROM from the famous Burgess Shale site (Yoho National Park) in the UNESCO World Heritage Canadian Rocky Mountain Parks, British Columbia over the past three decades, and examined by PhD student Martin Smith along with U of T EEB and Geology assistant professor and ROM palaeontologist Jean-Bernard Caron.

Lead author Smith said: "Previously, all knowledge of Nectocaris came from a lone specimen described in 1976. Due to the ambiguous characteristics evident on that specimen, Nectocaris has remained unclassified until now.

"Our study reveals that Nectocaris is similar to known members of the modern cephalopod group, which includes squid, octopus, cuttlefish and the nautilus, as well as common fossils such as ammonites and belemnites, which are now extinct."

[...] "Our findings mean that cephalopods originated 30 million years earlier than we thought, and much closer to the first appearance of complex animals in the 'Cambrian explosion.'"