Seedlings with no leaves

You don't say what they are or where they are. I have experienced damping off with cabbage seedlings, but they had leaves. Slugs are more dormant at this time of the year because of the cold.
I have googled the condition, but found nothing to help.

I should have said - they are (were) Basil seedlings in a heated propogator.  I have seen a slug trail on the lid  I think it must be him, I think they would have fall over with damping off.
Very annoying since it's only February.