What's he been eating? That's the usual cause and it is rarely anything to worry about. If he's been eating poop, it's worth getting a fecal check done for worms.
Oh phew!! Thanks! I thought he was only going in the bath because there is never any in his enclosure but clearly he's getting there first! That's a relief, Love my lil dude I don't half worry about him! I say him... I know it's too early but he's tucking his tail to one side... Anyway thanks so much!
He's been eating rose petals and baby leaf salad mostly, some dandelions, parsley, cabbage and various other bits but they're his fave I'm expecting my grow your own weed pack to arrive tomorrow, he's only been with me three weeks so diet will improve shortly. He went to the vet last week for a bad eye and has been on antibiotic drops this week, the eye is healing nicely just a tad concerned about this discolouration .
It's one of their less endearing habits - eating poop. Doesn't do any harm. As it's his own poop there's no increased risk of worms... it's random bird and animal poop found outdoors that's likely to have worms.
My bubba, african spurred tortoise do have that, too. I did my tried a soft toothbrush (his groomng hygiene, lol.) It can come from cut up greens, similar as a food dye.