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Square Cash appears to be acting more and more like a bank.

The Venmo-like service started as a way to simply send money to friends and family online, but it has recently been adding ways to spend the money that you receive and store in the app.

The next step? A physical Square Cash debit card, it seems, based on a photo tweeted by Square CEO Jack Dorsey on Thursday night.

my wallet these days pic.twitter.com/l8ug8bjpzT — jack (@jack) April 14, 2017

The all-black card was the first hint, since Square had prototyped a similar-looking payment card back in 2014, but never launched it.

Square has already introduced a Square Cash virtual debit card to buy stuff online — Dorsey said at Recode’s December Code Commerce event that he was using it as his default payment method. That was followed by an Apple Pay integration, so you could tap your phone in a store to pay with money stored in Square Cash. To some people, a physical card might seem a logical next step.

A Square spokesperson declined to comment on my educated guess that this is a Square Cash debit card in the photo. But I’m just going to say it is.

The real question: Why would someone want it? That I don’t really know. At Code Commerce, I asked Dorsey this very question when talking about the Square Cash virtual card.

“It’s crazy to think about, but people just want a more modern interface to their finances,” he said at the time. “Something that’s simple and straightforward and modern really wins.”

Dorsey went on to give examples of parents who send money via Square Cash to their kids in college, who can then go and spend it online or in stores without needing their own bank or credit card account. But that seems like a pretty fringe case.

Plus, a physical card is certainly not “a modern interface” — especially for a digital-first company like Square.

The only idea I can come up with is that Square may end up incentivizing Square Cash users to spend their money at Square brick-and-mortar merchants, since the company would make money from both sides of those transactions. And because not all merchants accept the Apple Pay service necessary to accept Square Cash virtual cards, a physical card would be needed for broader adoption.

“There’s huge long-term promise of what Square can do as a two-sided network,” Square CFO Sarah Friar told me in an interview in December.

Even, it seems, if that means using plastic.

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