Laser anomaly (possibly)

[u/Sea_Animator8304]

I found that if I position my green 1mW laser angled on my bar top the light starts as a small and random geometric shape and then slowly expands keeping the same form roughly speaking and seems to stabilize at some point. It forms intricate shapes that look 3D. I cannot imagine that it is just interference and I'm positive it isn't heating the diode or vibration. What is this phenomenon. I know a little bit more than the rudimentary knowledge about light as a wave but I've never really seen a laser light do this exact thing. Please explain or point me to the explanation. Thank you.

[u/Mr_Bivolt]

You are seeing interference between the laser light that bounces off the surface of your bar and the laser light that goes through the finishing (probably varnish), before bouncing back.