I know that when any Lithops is left out in bright, hot light, such as we have in our Sub-tropical Paradise, it can melt down like an ice cream cone, eventually. I've never done that with mine. But they do like bright light, so I occasionally set them out on the balcony in the morning for a few hours. A few days ago, it was more than a few. I got a phone call and had to head to work in a hurry.
In the sun for a few extra hours, most Lithops do just fine. Most of mine did, though they grumped at me.
But some are not so tolerant of sunshine.
|From Wikipedia, "Sunburn"|
I didn't realize what a minor case of sunburn looked like in a Lithops. Now I know. They get...pale, not pink. I learned this from Steven Hammer's good book.
This poor little creature looks like a Halloween ghost of its former vibrant self. Me, when I sunburn, I run around slathering aloe vera and screaming if anyone touches me. Lithops are more discreet. These Lithops will live to grow another pair, but I'll be more careful next time. Different Lithops species really do have different light needs.