A pony appeared on BART Tuesday, and this delighted many people on Twitter.

The posting from one @rodrlou shows us a rear view of the pony, seated near a door on a BART train on Tuesday.

A subsequent post from the person who was escorting the pony somewhere said, "Hey, I was with that pony, she belongs to my freind [sic]."

Other commenters chimed in to note that miniature horses are the only other animals besides dogs that are certified by state law to be human service animals (like for the blind), and that appears to be the case with this pony.

As BART confirmed via email with NBC Bay Area, "The station agent consulted supervisors who called the legal department for advice. The legal department advised the agent to allow the horse and person in."

Don't go looking for more ponies on BART, though, because clearly station agents are doing their jobs...

Related: Panhandling and Busking Ban Gets Thumbs Up From BART Staff Report