Is there a shape/icon to indicate something is safe?

There are lots of icons and shapes that we associate with danger and that indicate to excercise caution.

enter image description here Source, public domain High Voltage warning sign Source, CC2.5 BY-SA Skull and Crossbones Source, Pixabay Proprietary License enter image description here Source, CC4.0 BY-NC

To show a piece of hardware is safe, one could indicate that by the shape, the material or even by light (slowly breathing green or blue for example). That is not neccessarily trivial, but doable.

But, are there any graphical equivalents to indicate something is safe? Something that can be used in a presentation or a manual?

One idea would be a thumbs up, which is very ambiguous, or some pictogram on a blue background showing something being touched with bare hands, but maybe there's something better, more intuitive that I'm missing.

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