Surface tension? None known. Water has one of the highest surface tensions (certainly at anything approaching stand temperature and pressure) of all known materials. Mercury is higher, and still nowhere near a solid.
There is another property that can do what you’re thinking of: Viscosity. This is basically how easily the liquid flows over itself. There is a somewhat famous experiment where a container of [Pitch (tar like substance) is very very slowly dropping drops taking multiple years to form a single one.](https://en.m.wikipedia.org/wiki/Pitch_drop_experiment)
This material has such ~~low~~ *high*^1 viscosity that if you hit it with a hammer it will behave like a solid and can shatter rather than bend or deform.
^1 DOh!
Edit: A few folks have commented about glass. There’s a very widely spread myth about glass that it’s a liquid and flows under gravity. This was because very old windows were thicker at the bottom than the top, but this was due to how glass used to be manufactured – it had thicker and thinner ends, and when installing pieces in windows the installer would put the thicker side at the base because it balances easier while they get the framing in. It doesn’t actually flow though. The matter is muddied a little further because glass has an amorphous crystal structure, so when you shoot X-rays through it they scatter in a similar way to how they interact with liquids, but this oddity does not give glass the properties of a liquid.
The surface tension of mercury is high enough that it could be confused for a solid object, depending how thoroughly you observe it. Like, small amounts of mercury will roll around like little balls and look like little solid balls to the naked eye.
Of course, it is a liquid, and minimal further examination would show that, but it could be initially confused for a solid. I’m not sure if OP meant it would confuse a careful observer, or it could fool someone, like in the sense of a magic trick.
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