Humbled by a bubble

Okay, so here's where I admit that I did poorly in my college Physics class.  I came across some incredibly beautiful bubbles today, but mostly have questions about them rather than answers.  

They were at the end of surge channel on Bodega Head's rocky outer coast where ocean water had pooled after the tide receded.  Some yellowish foam had formed at the surface and the bubbles were within the foam.  They caught my eye because of their astounding colors — they were like jewels!

 

 

(Yes, if you're wondering, that's me reflected in most of the bubbles — in various positions while trying to balance over the water.)

I've seen lots of foam in the intertidal zone, and lots of bubbles, but I don't recall seeing bubbles like this before.  Have I been missing them, was I not paying enough attention?  How often does it happen?  Under what conditions?  Does it depend on something in the water, the type of light?

Some of them had patterns approaching fractals.  Look closely within individual bubbles below.  

 

I wondered if individual bubbles changed color, and indeed they do.  Here are two photographs of the same bubbles (see below).  If you follow a single bubble from the first to the second image, you can see the color change.  Sometimes it's subtle, other times the shift is quite dramatic. 

 

 

(Eric noticed that sometimes the swirling pattern looks like a nebula, like an image taken by the Hubble Telescope = a Hubble Bubble!)

Here's one more, just me playing around with the reflection of my hand.

There's some good introductory information (and illustrations) about colors in bubbles at this website.  I learned that the color of the bubble depends on the thickness of the film.  Unfortunately, I'm not experienced enough to explain more than this, but I hope you can appreciate these magical swirls!