Three penis designs at TW Blake Park, Preston, seemingly done in one continuous motion. Credit:Google Earth

Mysterious penis-shaped symbols have appeared on sports parks in Melbourne's north-east, primitive in design but following a technique similar to their more lauded predecessor, the crop circle.

Illustration: Matt Golding Credit:

Google Earth currently displays the penis designs on three parks in Preston and Thornbury, near Northland Shopping Centre, each with more than one attempt, of diverse sizes.

The area's mayor says the designs will require a "complex, costly and time-consuming" repair process.