Probably talking about hollow blocks or hollow bricks - like concrete blocks or "Tijolos baianos"

Construction and Building Materials : Strength correlation between ...In the tested prisms failure modes observed were through a splitting between the webs and the shells of the block. The webs restrained the shells of ...
www.linkinghub.elsevier.com/retrieve/pii/S0950061805000759

Troubleshooting... units with 1¼-in. thick face shells set by fully bedding the webs and face shells is only 8% stronger than the same wall set using face shell bedding. ...
www.masonryconstruction.com/industry-news.asp?sectionID=139...

[PDF] Understanding BS EN 771-3: Aggregate concrete masonry units
changes to the design dimensions of units. b) In the case of conical holes, or cellular holes, use the mean of the thickness of. the webs and the shells. ...
www.cba-blocks.org.uk/downloads/CBA Understanding EN 771 09... -

Re: masonry block propertiesThe webs and face shells are slightly thicker at the top than they are at the bottom if I remember correctly. This is a product of the forms...so that you ...
www.seaintarchive.org/group/seaint/mailarchive/2003c/msg008...

Alvenaria-
Cerâmica e Olaria ABCD Tijolos Baianos e Blocos Cerâmicos Venda direta ao consumidor. Entrega em todo o Estado de São Paulo. Tijolos baianos e comuns, ...
www.kiede.com.br/dirs/B2B_,045_Com,233rcio_entre_Empresas/C...