Metal Ice Cubes

[hairygrape]

I was given a set of four stainless steel "ice cubes", each with a face of about 20mm square. All the edges of the cubes are rounded off. I've never been keen on these artificial ice cubes be they made of metal or plastic but I just wonder what they are filled with as liquid can be heard inside if they are shake. I'm also curious as to how they were filled as they are completely seamless with no sign of a filling hole or weld anywhere even when examined with a lens. Can the stainless steel be cast around the liquid somehow? I've also noticed that some of the faces are more magnetic than others. Very curious and it's a mystery to me.

[jno]

perhaps the liquid inside needs room to expand as it freezes?

As to what it is, I don't know, probably unobtainium.

[Old_Geezer]

Wow, that's rare.

[TheChair]

There's a YouTube video about them (sorry, can't find it right now). In it they drill one out to discover that it's water. They also prove, together with the science and maths, that they are useless at cooling a drink compared with real ice cubes.

[hairygrape]

Thank you all. I'll try to find that YouTube video.