ST. LOUIS - It's something you may not have ever noticed: a hippo sitting high atop Washington Avenue! But Emily Dittmer did, and she wonders about it every time she walks by.

It lingers 11 stories above Washington Avenue, a rather large piece of art hidden in plain sight. A hippo that's been on the edge of 1509 Washington Avenue since the mid-90s, thanks to Bob Cassilly and his crew of eight.

"He was commissioned by this group to produce, I think it was like 12 hippos," said Kurt Knickmeyer. "They were cut at various depths to make them look like they were immersed in water."

Those hippos are still being climbed on in Riverside Park in Manhattan. But this guy was more or less leftover.

"Usually you end up with kind of a hodge podge of leftovers when we get done with projects, and this was put together, and then brought here," said Knickmeyer.

What you can't see from the street is the texture, the detail, the extra effort that went into making this animal seem more real.

"He made a plaster piece, covered it with an oil-based clay. And then there was Schwartz Taxidermy, it was kind of a famous St. Louis taxidermist, he went over and got some hippo and elephant hide, and he carefully pushed the hide into the oil-based clay to get this outside texture," said Knickmeyer.

It is one of many incredible pieces, a hint at what was to come at City Museum.

"I think that's just how Bob is. Let's stir things up. Let's make this big hippo and put it up on the corner of this building and see what kind of response we get. I mean, look at the City Museum. It's the same thing," said Bobby Heinemann, who has been with Cassilly Crew since 1992. He says the hippo was the first job he walked in on.

Thankfully, this kind of magnificent art is still being created by the Cassilly Crew, because Bob Cassilly left behind more than art. He left a legacy that continues to inspire.

Next week's question is from Lisa Goff in Mascoutah. She wants to know why Panera restaurants are called St. Louis Bread Company here, but Panera everywhere else. Check out Hey Heidi next week for the answer.