Gram-positive Eubacteria is a group of bacteria, the great majority of whose members display unique staining patterns when exposed to certain gram stains (hence making them gram-positive). Actually, not all of these bacteria are gram-positive; some are placed in the group because they are molecularly similar to the gram-positive bacteria. These bacteria contain more peptidoglycan in their walls, but are structurally less complex than other bacteria. There are both photosynthetic and chemoheterotrophic members of this group, the majority being chemoheterotrophic. Many of these bacteria are suited to survive harsh conditions because they produce endospores, "cells within cells" that have no metabolic function and a dehydrated cytoplasm. Even if the outer cell dies, the endospore can survive extremely harsh environments. The first antibiotic (penicillin) could only target gram-positive bacteria.