Yellowstone Park, USA:

CINDER POOL
Temperature 196-198°F Dimensions 30 feet diameter. Depth 38 feet. Cinder Pool, once called Verma Spring, is a remote and isolated feature on the One hundred spring Plain. No trail leads to the spring and it is difficult to find. The spring is flush to the ground, with milky water and a clay edge. It is a very fragile and dangerous feature and extreme caution should be taken when approaching it. The spring boils and water pulses, but there is no visible outlet. The water is high in chloride and sulfate. On its surface, pushed to the edges, are small—BB to pea size—black, hollow sulfur beads, which are extremely fragile. No one yet knows exactly how the floating beads form. The beads are composed of sulfur, quartz, feldspar and obsidian rhyolite. When dried they bum freely.

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Ok, but most of our Martian BB/blue berries (lol) are not hollow. I do remember seeing ONE that was though. Not all of the hydrothermal erruptions are alike at Yellowstone, nor do they produce the same results. If Meridiani was similar to Yellowstone at one time, even with little or no oxygen, it must have been quite a site.

As for interesting features, I'd like to know what these 'spikes' are... cones?

When I first saw that image (ESA's Mars Express took one of it in color), I thought of this Guelb:

The Guelb Moghrein, Mauritania (Many guelbs in Mauritania!)

[I notice, too, that the exposed outcrop we see on the distant crater appears to be almost like a frozen wave. There are signs all around that crater that suggest an impact origin, but the wave form -- if it is real, and not one of those visual tricks we see on Mars all the time -- suggest that the "white" material may be quite pliable. And that crater too may have formed from internal rather than external forces.]

Yes, I remember seeing a closeup image of that crater during a JPL briefing and I remember seeing that 'wave'. The wave did give us a look into the inside of the opposite wall of that crater, but, as far as color, It looked like that wall was lighter due to sunlight... a very light shade of Orange. We'll see and know more.

[I'm just thrilled with all of it!]

LOL I know! It's like finding a new favorite place to eat or visit. lol