Quick 'old Excel' question

I'm 90% certain that there was a version of Excel that showed which cells had formulae in by a little green triangular notch in the bottom-right corner of the cell. IMO it would be quite useful to see at a glance which cells have formulae in, but I can't remember for the life of me which version of Excel had it. Ideally I'd like to replicate the behaviour in LibreOffice Calc. I've tried it in Excel 2007 and 2021, neither of those do it. I wonder if it might have been 2010. - edit - I googled it and apparently screwy cell data can invoke this feature (e.g. Excel detecting a formulae that it thinks isn't doing what's intended, or if I put: Code: '00020 In a cell then it will flag it because it thinks it's wonky. Maybe that's what I'm remembering, because it seems unlikely that there would be two very similar markers that mean different things. Still, a marker to say "a formula lives here" would be nice!