Obtained from Thomas Ray by email on May 09, 2022. It is an image of the Monstera tenuis (formerly gigantea) seedlings described by Strong & Ray (1979), who placed a box next to some growing seedlings, and came back 2 months later to find this. The opening of the box is marked by the stick.
Strong Jr, D. R., & Ray Jr, T. S. (1975). Host tree location behavior of a tropical vine (Monstera gigantea) by skototropism. Science, 190(4216), 804-806.