The tamarillo is also called a “tree tomato”. It doesn’t have much of an aroma to speak of, and the purple ones look like oblong plums (there are also red and yellow versions). The outer skin is much thicker than a tomato, and inedibly bitter. The flesh inside is orange, and softly firm – similar to a non-grainy tomato tecture, but more firm like a persimmon. Inside the flesh are small seeds, encased in a dark red juicy pulp. When cut, the juice tends to run out a little bit, and looks like the juice from a blood orange (very red). The taste is tangy, and savory-sweet. It tastes like a deeply ripe tomato, with a hint of passionfruit and guava. The aftertaste is mostly savory, like the aftertaste of a somewhat tart fresh tomato.
There’s a wikipedia article at: https://en.wikipedia.org/wiki/Tamarillo