Golf Buddies

The nearby Hotel Golf Course has a couple of unusual residents. Not originally from around here, they are no doubt older than most of the local population, so can claim to be well established. The one in the picture is the male, with a 1 metre diameter shell. They live in a burrow under the large tree at the side of the golf course. The female, when I took this picture, was well hidden deeper in the burrow. If I can ever catch them outside, I'll try and get a view that does their size justice. I wonder what they make of golf balls?