:)...that reminds me of at least one source of religious history claimed that the "altar" as we know it in most Christian Churches came about during the Medieval period. The Host was left on the Communion table so that pilgrims could partake at any convenient time. There was a problem with dogs getting in the Cathedrals and eating the Communion. So the good fathers would build a "fence" around the table. Thus the fence-like altars we see today. True? Who knows?
The "fence" in any major cathedral is quite tall and has a gate with a lock. I'd thought it was to protect the vessels, particularly if they were silver or gold.