Found on a beach in Brisbane, Australia. Only a few cms of it was visible but I dug the rest of it out, it was about 20cm in length.
That is a Priapulid worm, also known as a "penis worm". In its own phylum, Priapulida. https://en.wikipedia.org/wiki/Priapulida
$\begingroup$ Thanks, I would never have worked it out as it is quite different looking from the other photos of Priapulid worms available through google search (i.e. I couldn't find an example of a similar looking specimen). Thanks for helping. $\endgroup$– SeanOct 31, 2018 at 4:55