Figure S1. Lithocolla globosa

Figure S1. Lithocolla globosa SnP. A-B) Agglutinated cells from enrichment with sediment still

present. Surface view (B) showing attached mineral particles. C-O) Cells from culture, fed on

Navicula (C-G), Isochrysis (H,L-O) and Phaeodactylum (I-K). C-D) General view of same cell.

Note nucleus (in C) and ingested diatoms (in D), orange globules (D inset, bracket) and layer

(D inset, arrowhead). E) General view of cell. Note nucleus, orange globules and greenish

digestive vacuoles. F-H) Examples of intact filopodia. Note that filopodia degrade rapidly under

exposure to bright light. I-J) Individuals with 2 (I) and 3 (J) nuclei, relatively commonly observed

in culture. K) 'Re-agglutinated' cell one day following addition of chalk dust (as fine calcium

carbonate mineral inclusions) to culture. Note mineral particles inside and on the surface of the

cell, resembling the agglutinated cells from enrichment in (A-B). L-O) Pseudoseries of different

individuals showing mineral inclusions found in cells (arrowheads), 20min (L), 23min (M), 47min

(N), 60min (O) following addition of chalk dust to mineral-particle-deprived culture, indicating that

mineral particles are ingested by the cell. Differential interference contrast, scalebars are 20μm

(A-K, all images at same scale), 10μm (L-O).