The adult coloration of M. balfouri is striking, a vivid blue, though some red and amber variants have been seen very rarely.

[2] A unique behavior of this tarantula is that it is communal, to the point that mother spiders care for the young, even attacking potential predators if they get too close to her egg sac.

In captivity, multiple males and females of different ages may live together without attacking one another, provided that they have enough food and proper care.

[citation needed] When threatened, M. balfouri gives a characteristic “threat pose,” rearing up on the hind legs and baring the chelicerae.

Further provocation will lead this tarantula to deliver a fast strike and bite, especially if protecting an egg sac.