That is an oldie David.
**Ribs on the four sides of a terra cotta block help mortar, stucco and plaster adhere. **
But in your case, it has gone beyond it’s useful life.
Although manufactured as early as the 1890s, structural terra cotta blocks were most common in the first quarter of the 20th century. Stucco was the usual exterior cover, hence the popularity of the building material in Mission and Mediterranean Revival style homes.
The blocks can also be found in military buildings and gas stations built as late as 1940.
Hollow tile blocks have also been used in commercial style buildings, but usually not as a component of a structural wall over three stories.
Here the blocks are often used as fill between steel structural elements and for fire resistant wall construction, including interior partitions.
The only unfavorable trait of the blocks is that they are vulnerable to damage, even fragile, under certain circumstances. I’ve seen damage to individual units from mishandling or mistreatment after installation. Drilling into the blocks to anchor another material can be difficult.
It often results in a blow-out of an area of much larger diameter than the intended hole. The brittle nature of structural terra cotta should probably be a concern for people living in an area with the potential for a seismic event.
Fortunately, the compressive strength of the shells and webs of these terra cotta blocks are much stronger than what you would expect from a building material made from the same stuff as flower pots. In many buildings, the blocks have lasted 75 years or more without problems, and can be expected to last for many more decades.
Not quite the choice for stuctural integretity.