So I saw a bumper sticker today that said “I Believe” and had some sort of symbol on it. From far away it looked like a question mark, but on closer examination it seemed to be a sun, on top of a chalice, with a cross on top, like some sort of weird ice cream cone. I asked the driver, and he said it was something that sounded like “montrice”, and said it was a Catholic symbol. Does anyone have any idea what it is?
The word he said was “monstrance”, which is a presentation of the host for communion.
Like this. A consecrated host is placed in the glass enclosure in the middle and the monstrance is placed on the altar for veneration by the congregation. It’s a devotion that’s pretty much fallen out of fashion, though many parishes do an occasional Adoration of the Blessed Sacrament.
Some even do what’s called Perpetual Adoration, where members of the congregation sign up on a schedule to be in the chapel (usually a small side chapel, not the one where the whole congregation meets) so there’s always someone there worshiping.
And the word “monstrance” comes from the same Latin root as “demonstrate”, because it’s used for display.
The word “monster” comes from the same root. Apparently, the freak show has a long history.
Practices differ around the world. In my parish the Host is displayed for several hours every day for adoration, and there’s Benediction a couple of times a week.
I remember as a kid hearing that there was a monstrance on display in the Catholic Church in the next block. I snuck down there to see it, but there was no big ugly creature, just a fancy cross with some kind of white disk at the intersection of the arms. 
Still huge in many parts of Latin America.