What makes these depressions?

[MBay Pete]

A question for those who know.... What makes the craters in the sandy mud between the high and low tide area on many beaches in Moreton Bay. I see them all the time when I go and pump yabbies and was wondering if it was from crabs burying before low tide. The depressions vary on size from dinner plate size to almost a metre across and around 150 mm deep.
Have asked friends but no-one had an answer, hopefully someone here will be able to satisfy my curiousity.

Thanks
Pete

[snapperbasher]

Stingrays usually

[Still_Dreamin]

Yep, stingrays and occasionally big Flatties

[scottar]

Stingrays, fish and blokes with yabbie pumps

[StevenM]

Rabbits I tell ya

[MBay Pete]

Thanks all....I will have to keep a lookout for rabbits with yabbie pumps perhaps...........

[Volvo]

Yep Pooooooofter Wabbits that wake up n find a hair /or is hare up their ace!!???...

[robfish 1]

I once read an article by Rod Harrison, who had actually observed trevally making those circular depressions on the high tide, as they grubbed in the sand.
Never observed them myself, being stuck in beautiful Melbourne - but it may be on the money, as he's always been a font of information.

But then again, I wouldn't dismiss those pesky wabbits with yabbie pumps, either!