There are four pictograms hanging on the wall of the altar. I don't know what they are

There are four pictographs hanging on the wall of the altar, which are ancestral tablets of seal script, not pictographs.

Seal script is a general term for big seal script and small seal script. Oracle Bone Inscriptions, 3000 years ago, is the earliest recognizable writing handed down, mainly used for divination. The brushwork is thin and powerful, with many straight lines. There are Fang Bi, round pen and sharp pen, and there are many "hanging needles" for writing. Big seal script refers to inscriptions on bronze inscriptions, bronzes and six-country scripts, which retain the obvious characteristics of ancient hieroglyphics. Xiao Zhuan, also known as "Qin Zhuan", is a commonly used character in Qin State and a simplified font of Da Zhuan, which is characterized by uniform and neat glyphs and is easier to write than Wen Shu.