The biggest news last week wasn’t another one of Elon Musk’s Twitter tantrums, but the announcement that scientists had finally solved one of fusion energy’s greatest challenges — successfully extracting more energy from a controlled fusion reaction than they put into it.

Fusion power, which has always seemed science fiction and about as plausible, suddenly took a very tangible step toward reality.

That does not mean that someone will connect a fusion power station to the grid tomorrow or even in 10 years. But it does give a boost to a field that has recently been buzzing with confidence. A confluence of advances has led to a tidal wave of startups and investments. In the past year alone, investors have bet $2.7 billion on fusion startups.

Many of those investments were part of massive rounds that raised hundreds of millions of dollars in capital. No surprise: fusion power is hard technology, and it will take years of collaborative research and development to bring it to fruition.

But what if you’re an investor who doesn’t have tens of millions in dry powder earmarked for merger? Fortunately, not all fusion startups are unicorns. There are many new companies looking for new ideas for power plants, as well as software companies and suppliers hoping to build the supply chain for what could be a $40 trillion industry, according to to Bloomberg Intelligence.

Here are five companies we’re keeping an eye on.