Why do my snails enjoy grazing burnt wood?

[counterbalance]

So I decided to thoroughly clean my snails' tank yesterday, including dishes and twigs, and, in order for the twigs to dry faster, I put them near fire. Some of them got burnt slightly. Today I've noticed that nearly all of my snails are very interested in those burnt spots. Is it even safe for them to eat (normally, they won't eat anything that's bad for them, but I still wonder), and, if so, what is it about the burnt wood that can be so interesting to them? Is there something that they don't get with the food that I give them that they found in such an unusual source?

[pasi9]

The only thing I can think of burnt wood providing is carbon. But I'm not sure why a snail would crave that?
I can't imagine it's bad for them. I know ash is very drying when they try to climb over it so some people use it as a snail/slug deterrent, but that wouldn't be an issue with a bit of charred wood.

Maybe it reminds them of barbecues.

[counterbalance]

Thanks for replying, pasi9. I still fail to understand exactly what happened, but now that the snails cleaned the charred parts that are no longer blackened, they use their twigs, as before: for sleep, as bridges, etc.